Episode 12

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Published on:

1st Aug 2025

S1E12 Manifest Destiny: Westward Expansion & Mexican-American War | American Yawp Chapter 12 Explained

In Episode 12 of Star-Spangled Studies, Dr. G unpacks The American Yawp Chapter 12—how “Manifest Destiny” drove U.S. expansion across the continent. Key topics include:

• Origin of the term “Manifest Destiny” by John L. O’Sullivan

• Racial ideology & Anglo-Saxon supremacy driving expansion

• Indian removal wars & the Trail of Tears

• Texas Revolution & Tejano contributions (Juan Seguín)

• Spot Resolutions & Lincoln’s challenge to Polk’s war claim

• Mexican–American War: causes, conduct & Treaty of Guadalupe Hidalgo

• 1848 Gold Rush: global migration, Chinese miners & racial violence

• Filibustering expeditions & expansionist ambitions

• Historiographical perspectives: frontier thesis vs. New Western History

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Episode 12 examines Manifest Destiny—its origins, racial justifications, Indian removal, the Texas and Mexican wars, the Gold Rush, and its profound impact on America.


Transcript
Speaker:

Hello y'all.

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It's me.

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It's me.

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It's Dr.

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G.

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And welcome back to Star Spangled Studies.

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Imagine this, it's April of 1853.

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You are Amelia Stewart Knight,

the mother of seven children, and

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you are pregnant with your eighth.

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You've just packed your life

into a covered wagon in Iowa and

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you're staring down the barrel

of a:

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The weather is miserable In your

diary, you write cold and cloudy this

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morning and everybody out of humor.

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Almira says she wished she had was

home, and I say, ditto home, sweet home.

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End quote.

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You are surrounded by mud sick children

and the constant threat of disaster, yet

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you are also part of something immense.

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A few weeks later, you look out across.

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A river crossing and you note quote,

there are 300 or more wagons in sight,

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and as far as the eye can reach, the

bottom is covered on each side of

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the river with cattle and horses.

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End quote, what could possibly have

motivated millions of Americans,

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people like a million knight to

endure such hardship moving westward?

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What powerful idea was pulling them to the

west, convincing them that this brutal.

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Dangerous journey was not

a choice, but a calling.

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The answer is a phrase that sounds both

grand and ominous, manifest destiny.

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In this episode, we're gonna explore the

belief that the United States was divinely

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ordained by God to conquer the continent.

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We'll unpack its justifications, witness

its violent consequences, and see how

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a single idea, a mix of high-minded

idealism and brutal racial logic.

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Set the stage for the American Civil War.

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So let's go.

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The idea of American expansion

westward was not new.

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Of course, we've seen it before

in our previous episodes.

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It was baked into the colonial

project right from the very start.

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But in the 1840s, this longstanding game

and impulse got itself a new name, a

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new slogan, a new brand, if you will.

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It came from the pen of a New York

editor, a man named John Lewis O'Sullivan.

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He wrote in an 1845 essay for the United

States Magazine and Democratic Review.

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And O'Sullivan was arguing for the

annexation of the Republic of Texas.

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He blasted European nations for

trying to interfere writing that

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they were attempting to check.

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And here's the famous line from

that quote, the fulfillment of our

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manifest destiny to overspread the

continent allotted by providence

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for the free development of our

yearly multiplying millions.

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End quote.

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There it is, manifest destiny.

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Man of us, meaning obvious or clear

destiny, meaning inevitable faded.

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O'Sullivan had bottled

lightning quite literally.

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Well, maybe not Literally.

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He gave a name though to the belief

that was already deeply felt across

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the country that the United States

was on a special mission from God.

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As our textbook outlines this

doctrine rested on three core

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pillars, three articles of faith.

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The first was the belief that the

strength of American values and

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institutions, namely democracy,

Protestantism, and Liberty justified.

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The claim, the moral claim to be

the leaders of this hemisphere

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and quite possibly the world.

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The second was that the lands

to the west were destined for

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improvement, both politically and

agriculturally, and specifically.

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In the American style, the thinking

went that the people already living

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there, native Americans and Mexicans

were not using the land to its fullest

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potential and thus needed to be shown the

right way or removed so that the right

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people could do that in the right way.

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And third was the conviction

that God and the Constitution

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had ordained this mission.

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This wasn't simply something political.

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It was a sacred religious duty to

redeem the continent, to democratize

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the continent, the American way.

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But we have to be careful right here.

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When O'Sullivan and others talked

about spreading democracy and freedom,

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they didn't mean it universally.

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Theirs was a vision with a

very specific racial lens.

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The language of providence and progress

served as a convenient, high-minded

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justification for what was at its

core, a project of racial conquest.

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While O Sullivan spoke of a divine

mission, he also wrote of the quote,

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irresistible army of Anglo-Saxon

immigration pouring down into California.

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This wasn't an accident.

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The improvement of the lands, in his

words, was seen as a task for a very

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specific people, white Anglo-Saxon

Americans, his irresistible army

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of Anglo-Saxons, as he put it.

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By the 1850s, historians argue

that American expansionism was

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driven by a virulent new form

of racial ideology Anglo-Saxon.

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This wasn't just simple prejudice, it

was a scientific belief, scientific,

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in quotation marks that Anglo-Saxon

race was innately superior to all

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other races, and more specifically

that it was higher in the hierarchy.

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Then black, native American and Mexicans,

whom they viewed as biologically inferior

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and that they were doomed to be displaced.

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Or that they were doomed to

be dominated and enslaved.

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So when the expansionists said that

Providence had quote allotted the

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continent to them, they meant it had been

given to the superior Anglo-Saxon race,

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and those were the, their words, the

language of this divine mission to spread

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liberty was fused with a racial mission

to ensure Anglo-Saxon dominance or.

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White supremacy.

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This progress they envision was predicated

on the belief that non-white peoples

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were incapable of self-government

or of properly using the land.

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This potent brew of nationalism.

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Racialism and quasi-religious fervor

was championed by a political force

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known as Young America Movement,

strongest in the Democratic Party.

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This movement saw the expansion as a way

to unify the nation to distract from the

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growing bitter divisions over slavery by

focusing on a shared project of national

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greatness and economic interdependence.

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The great thinker Ralph Waldo Emerson

captured the spirit of this new movement

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asking quote, in every age of the

world, there has been a leading nation,

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which should be the nation, but the

states who should lead the leaders.

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But the young Americans end quote.

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But not everyone was so captivated.

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A young wig congressman from Illinois

named Abraham Lincoln, saw the hypocrisy.

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He satirized the young American

saying his quote, desire for land is

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not selfish, but merely an impulse

to extend the area of freedom.

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He's very anxious to fight for

the liberation of enslaved nations

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and colonies provided always.

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They have land end quote.

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Lincoln put his finger on

the central contradiction.

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This grand mission of liberty was

in practice, a mission for land,

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a mission that would run roughshod

over anyone who stood in its way.

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So what happens then when

the idea of manifest destiny?

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Armed with a sense of divine and

racial superiority and armed with

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guns and weaponry meets the people

already living on the land that

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it covets and wishes to take over.

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The answer is another round of the policy

that has been called Indian removal.

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The process was brutally

road tested in Florida.

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The first and second seminal

wars were not just about land.

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They were deeply entangled with

the institution of slavery.

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Plantation owners in Georgia and the

Carolinas were terrified by the presence

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of a powerful autonomous seminal nation.

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Offered refuge to escape

slaves, free black people, and

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escaped slave known as black.

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Seminoles lived and fought alongside

the seminal Native Americans,

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creating a powerful alliance that

horrified the slave owning South.

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US Commander General Thomas Jessup was

explicit calling the second seminal war

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quote, a Negro, not an Indian war end

quote, and he feared that if the seminoles

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weren't crushed, the rebellion would

spread to plantations across the south.

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These wars were long, they were bloody,

they were expensive, but they established

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a model used military force to remove

Native American peoples and secure

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land for white settlement and slavery.

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It is a removal model that

was used over and over again.

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This model was applied on a

massive scale once there was

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the Indian Removal Act of 1830.

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This act gave President Andrew

Jackson the authority to negotiate

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treaties to exchange Native American

lands in the east for territory

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west of the Mississippi River.

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Publicly Jackson framed this as a

benevolent paternalistic sus policy.

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We had discussed this

in a previous episode.

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He claimed that the removal would quote,

separate the Indians from immediate

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contact with settlement of whites, and

that it protected them, allowing them

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to become more Christian and civilized.

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Those were his words, which

of course was nonsense.

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The Cherokee Nation

provided the most tragic.

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Refutation of this claim and more

than any other group, the Cherokee had

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actively embraced the civilization policy.

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They developed the written language.

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They adopted a constitution based on

modeled on the United States Constitution.

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Many converted to Christianity.

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They became successful farmers,

and in some cases they even

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became slaveholders themselves.

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They used American tools to defend their

rights, including lawsuits and petitions.

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In fact, in an 1836 petition protesting

their removal, Cherokee leaders laid

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out the bitter irony of their situation.

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Quote, you asked us to throw off

the hunter and Warrior State.

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We did.

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So you asked us to form

a Republican government.

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We did So.

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You asked us to cultivate the Earth.

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We did.

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So now you demand we seed our

lands that we will not do.

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End.

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Quote.

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Their pleas and their use for equality

in the justice system were ignored.

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Under President Martin Van Buren, the

US military enforced their removal.

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In the winters of 1838 and 39, some 16,000

Cherokees were forced to march westward on

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what became known as the Trail of Tears.

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The journey was devastating,

overloaded, undersupplied.

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It was racked with disease and at

least 4,000 people, and I would argue

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probably more died along the trek.

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This was not their for their protection,

nor did it protect them at all.

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This was a death march, driven by land,

greed, and justified by the ideology.

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Of Manifest destiny.

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This history forces us to rethink

about how we talk about the West.

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The traditional story popularized by

historian Frederick Jackson Turner

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in 1893 is the frontier thesis.

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Turner saw the west as a process, a

moving line what between what he called

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quote, savagery and civilization.

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He argued that this process of

taming the wilderness created

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American democracy and individualism.

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And that it all came to a neat

close around:

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Frontier Line disappeared.

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But in the late 20th century, a

group of scholars known as the

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New Western Historians powerfully

challenged this narrative

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historian, Patricia Nelson Limerick.

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In her book, the Legacy of Conquest argues

that we should think of the West not as

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a process that ended, but as a place with

an unbroken past for Limerick, the story

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of the West is not a romantic adventure.

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It's actually a story of conquest

and the consequences of that conquest

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over land, water, over resources,

and specifically over race are

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still with us and haunt us today.

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The West isn't a closed chapter.

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It's a place where the conflicts of

the 19th century continued to play out.

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Another key historian,

Richard White, introduced the

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concept of the middle ground.

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Now he focused on the Great Lakes

region and he showed that while the

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story, there wasn't always one of simple

conquest, it was often a complex dance

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of negotiation accommodation, and it.

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Creative misunderstanding we might say

between Native Americans and Europeans.

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They built a shared world, a

middle ground where neither side

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could fully dominate the other.

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So together these historians

forced us to see the west as of

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never something that was empty.

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It was never an empty land really

waiting to be settled or even civilized.

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It was a crowded, complex place.

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Hundreds of different nations lived

there and called it their own homes.

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And the story of the westward expansion

is not a simple heroic tale of progress,

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but a complicated and often brutal

story of violence and conquest, of

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displacement, of enduring legacies

that we still feel the echoes of today.

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Manifest Destiny's.

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Next target after Native American

groups was this Sister Republic

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next door, Mexico, and the quest

for the land that Mexico had.

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Owned would push the United States

into a war that many, including

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a young Abraham Lincoln saw as a

profound betrayal of American ideals.

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The story begins as so many do in this

era in Texas, after Mexico encouraged

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American settlement in the 1820s.

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Tensions quickly rose over slavery,

which Mexico had outlawed prior to this,

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and the settlers who came to this Texas

area refused to abide by Mexican law.

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This friction culminated in

the Texas Revolution of:

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It's often portrayed as a simple conflict

between Anglo Texans and Mexicans, but

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in reality, it was much more complex.

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Many tejanos.

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Mexicans of Mexican descent also

fought for an independent Texas.

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One of the most prominent was Juan Sagu,

a respected leader from San Antonio.

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Sagu raised a company of Tejano

volunteers and fought bravely throughout

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the revolution at a memorial for

the fallen defenders of the Alamo.

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In 1837, he declared companions

in arms, thus remains, which we

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have the honor of carrying on.

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Our shoulders are those of the

brave heroes who died in the Alamo.

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I invite you to declare to the

entire world, Texas shall be free

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and independent, or we shall perish

in glorious combat end quote.

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But his story ends in tragedy.

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After Texas won its independence,

the flood of Anglo-American

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immigrants brought with them.

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Intense racial prejudice.

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Despite his service in fighting for that

Texas independence, he and other tejanos

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were viewed with suspicion and hostility.

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He was accused of being a traitor

and he was forced to flee the very

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nation he had fought to create.

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He would lighter right of his painful

exile, lamenting that he was in

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his own words, quote, A foreigner

in my native land end quote.

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His experience was a bitter testament

to the racial hierarchy that Manifest

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Destiny was imposing on the West.

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The Texas Question festered For

nearly a decade, president's Jackson

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and Van Buren resisted annexation,

fearing that it would mean war with

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Mexico, and more importantly, that

it would ignite the explosive issues

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of slavery in the national politics.

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But the expansionist president, James K.

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Polk had no such qualms about this.

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He pushed annexation through, and

in:

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War was now pretty much inevitable.

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The United States and Mexico disputed

the southern border of Texas, Mexico

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claimed that it was the Nassis

River, the historical boundary,

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while the US and Texas claimed the

Rio Grande 150 miles further south.

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In early 1846, president Polk who had

his eyes on acquiring California as

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well ordered General Zachary Taylor and

his troops into the disputed territory.

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A clear provocation.

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On April 25th, 1846, Mexican

cavalry attacked an American.

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Polk now had his pretext for war.

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On May 11th, he sent a dramatic war

message to Congress declaring quote, the

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cup of forbearance has been exhausted.

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After reiterated Menas, Mexico has

passed the boundary of the United

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States has evaded our territory and

shed American blood upon American soil.

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End quote, the phrase was electric.

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American Blood on American soil.

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Congress swept up in patriotic

war fervor quickly declared war,

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but not everyone was convinced.

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The freshman wig congressman from Illinois

Abraham Lincoln stood up and challenged

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the president in a series of resolutions

that became known as the spot resolutions.

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Lincoln demanded that Polk

identify the exact spot on

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the map where blood was shed.

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He asked whether that spot is or is

not within a settlement of people,

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which settlement had existed ever

since long before the Texas Revolution,

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whether the people of that settlement

have ever submitted themselves to

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the government or laws of Texas

or of the United States end quote.

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Lincoln was implying that many

suspected at the same time that the

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spot was not American soil at all,

but Amer, but Mexican territory

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inhabited by Mexicans, and that Polk

was deliberately provoking a war.

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Lincoln's resolutions were tabled.

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But his skepticism had been validated

by modern historians like Scholar Amy

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Greenberg in her book, A Wicked War, and

she argues forcefully that the conflict

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was exactly what Lincoln suspected.

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It was a war of conquest

engineered by the President and

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started with a presidential lie.

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Greenberg shows that Polk was driven

by a greedy imperialistic vision of

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manifest destiny and was determined to

acquire California by war if necessary.

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The claim that American blood had

been shed on American soil was a

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deliberate deception to rally a

reluctant country to an aggressive war.

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The conflict was not a

defense of American territory.

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It was an invasion of Mexico.

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The war was a decisive victory

for the United States, and in the

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1848 Treaty of Guadalupe Hidalgo,

Mexico seeded a vast territory.

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What is now the states of California,

Nevada, Utah, Arizona, and parts of

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New Mexico, Colorado, and Wyoming.

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It lost nearly half its land.

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The United States had fulfilled

its manifest destiny to stretch

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from sea to shining sea.

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But as we'll see though, this

victory came at a terrible price.

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The war with Mexico gave the United

States, California, and just days after

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the treaty was signed, a discovery

there would trigger one of the most

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frantic migrations in world history.

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But the Gold Rush was not just

the story of Plucky 49 ERs.

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I wonder where that San

Francisco team got its name.

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It was a global event that revealed

the violent racist underbelly

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of manifest destiny's promise.

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In January of 1848, gold

was discovered at Sutter's.

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The news spread like wildfire

and a flood of people poured into

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California searching for gold.

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The population out west exploded.

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San Francisco went from a sleepy

people in:

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a booming, chaotic metropolis of nearly

50,000 people just five years later.

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These migrants came from all over

the world, not just out east.

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They came from.

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Europe from Latin America and

in huge numbers from China.

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This gold mountain as the Chinese

called it was no paradise.

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It was a place of lawlessness.

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There was tons of racial conflict

and brutal violent exploitation.

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While white Americans often saw themselves

as the rightful owners and managers of the

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mind, they relegated ethnic minorities to

the hardest and least profitable labor.

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This was especially true for the

thousand of Chinese immigrants who

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arrived also seeking their fortune.

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They faced intense discrimination and

violence as well as legal injustices.

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We are fortunate to have a powerful,

firsthand account of this experience.

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In 1860, a Chinese merchant named

Panchi wrote a petition to the US

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Congress pleading for protection

of himself and his countrymen.

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His words paint a harrowing picture.

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He wrote, quote, we Chinese are

viewed like thieves and enemies.

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As we go on our way, we are

pushed and kicked and struck

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by the drunken and the brutal.

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Robbers, strip and plunder

wound, and even murder.

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Some of us end quote, punchy,

detailed, how Chinese miners were

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extorted by boatman, cheated out

of their claims by Americans and

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had their gold stolen by robbers.

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They dared not resist.

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Most damningly, he pointed to the root of

the problem, a legal system that refused

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to even recognize their basic humanity.

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He wrote, quote, when in the

administration of justice,

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our testimony is not received.

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Villains of other nations are

encouraged to rob and do violence to us.

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End quote, the gold that was supposed to

bring prosperity and fulfill the promise

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of the west instead created a landscape

of racialized violence where the blessings

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of liberty were reserved only for whites.

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The ideology of Manifest Destiny was not

confined to the North American continent.

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Its logic of American superiority

in hemispheric dominance had been

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articulated decades earlier in

the Monroe Doctrine, which we had

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talked about, which warned European

powers to stay outta the Americas.

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By the 1850s, this impulse took on a

more radical and sinister form with

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the phenomenon of filibustering.

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These were privately funded military

expeditions, essentially pirate

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invasions launched by American

adventurers to seize foreign territory.

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Men like William Walker tried

to conquer parts of Nicaragua

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and establish new slave regimes.

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While others dreamed of capturing Cuba for

the United States, though these schemes

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often failed and they ultimately did fail,

they show the boundless imperialistic

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ambitions that manifest destiny had

unleashed, and ambition now explicitly

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tied to the expansion of slavery.

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And that brings us to the

dark heart of the matter.

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Manifest Destiny was a powerful engine

of national growth, a force that

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pushed the United States across the

continent and onto the world stage.

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But it was an idea fueled

by a toxic mix of democratic

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idealism and racial supremacy.

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It led to the violent dispossession

of Native Americans, a war for

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conquest against Mexico, and

the creation of new arenas for

369

:

racial conflict and exploitation.

370

:

And in the end, it brought the nation

to the brink of self-destruction.

371

:

Ralph Waldo Emerson had seen it coming

as the Mexican American war began.

372

:

He wrote in his journal a very

chilling and prophetic line quote.

373

:

We will conquer Mexico, but it will be

as the man who swallows the arsenic,

374

:

which will bring him down in turn.

375

:

Mexico will poison us.

376

:

End quote.

377

:

The poison as it turned out, wasn't

Mexico or Mexicans themselves.

378

:

The poison was the questions that

came with all of the new land, with

379

:

all the new territory acquired in the

name of Manifest Destiny specifically.

380

:

Would this be free or would it be Slave?

381

:

Every new Acre acquired from Texas to

California became a battleground in the

382

:

escalating irrepressible conflict over the

future of slavery in these United States.

383

:

The dream of a continental empire

had inadvertently laid the path

384

:

to a possible national suicide.

385

:

The next time on Star Spangled Studies.

386

:

We'll see just how that poison worked.

387

:

Its way through the body politic as we

dive head first into the sectional crisis.

388

:

I'm Dr.

389

:

G, and I'll see y'all in the.

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About the Podcast

Star-Spangled Studies
Star-Spangled Studies is a college-level U.S. history podcast created by professional historian Dr. G—built for students, teachers, and curious listeners alike. Season 1 covers the era from 1865 to the present, using The American Yawp, a free and open educational resource (OER) textbook, as its guide. Each episode unpacks key events, movements, and ideas that shaped the modern United States—through rich narrative, scholarly insight, and accessible storytelling.

Whether you're enrolled in a course or exploring history on your own, you’ll get clear, engaging episodes that follow the chapters of The American Yawp. Bring your curiosity, download the textbook, and join Dr. G for a star-spangled journey through American history.

Free. Accessible. Thought-provoking.
This is your front-row seat to the story of the United States.
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