Chapter 16: Manifest Destiny & Westward Expansion

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Welcome to the Deep Dive.

We're jumping into Chapter 16 today, Manifest Destiny and its Legacy, covering 1841 to 1848.

That's right.

And this is a really dramatic period.

It's when the U .S.

stretches all the way to the Pacific.

Yeah, and it's not just about maps changing.

It's about

America grappling with itself and setting the stage for the Civil War, really.

Exactly.

So our mission here is to kind of walk through this crucial time.

We'll look at the key players, the big moments, and especially how this drive for expansion gets tangled up, deeply tangled up with slavery.

And it all kicks off with quite the political shock, a president dying.

Yeah, William Henry Harrison, elected in 1840, the big Whig victory.

Tippecanoe and Tyler, too.

Gives this incredibly long inaugural speech, catches pneumonia, and dies just four weeks later, April 1841.

Shortest presidency in history.

Boom.

Which leaves Tyler, too.

John Tyler suddenly in the Oval Office.

And nobody in the Whig party really planned for that.

Tyler was, well, he was a state's rights guy, technically a Whig, but really more of an anti -Jackson Democrat at heart.

Put on the ticket to appeal to the South.

Exactly.

The real Whig leaders, people like Henry Clay and Daniel Webster, they saw Harrison as, you know, someone they could manage.

A figurehead.

Tyler.

Tyler had his own ideas.

So you get this immediate clash.

Accidental President Tyler versus the Whig establishment led by Clay.

Total political warfare is probably the right term.

Clay pushes the Whig agenda, starting with a new national bank, the Fiscal Bank.

And Tyler.

Vetoes it flat out.

He's fundamentally against that kind of federal power.

So the Whigs regroup, try to be clever, rename it the Fiscal Corporation.

And Tyler vetoes that, too.

I mean, the Whigs are just beside themselves.

This was supposed to be their moment.

So they kick him out.

Pretty much.

The Whig caucus formally expels him from the party.

He becomes his accident, a president completely without a party base.

Wow.

So he stopped the bank.

What about the tariff?

That was another big Whig goal.

He tangled with them on that as well.

He vetoed their first major tariff bill, mainly because it included this scheme to distribute revenue from public land sales back to the states.

Which he saw as irresponsible spending.

Right.

He forced them to take that part out.

Eventually, he did sign a revised tariff in 1842, but it just lowered rates back to sort of the moderate 1832 levels.

Nothing like the high tariff the Whigs really wanted.

So Tyler, this accidental president,

basically single -handedly stopped Whig economic plan in its tracks.

He really did.

Through sheer stubbornness, you could say.

It left the Whigs furious and Tyler politically isolated.

Okay, so domestic policy is a mess.

What about foreign relations?

The chapter calls this the Third War with England.

Yeah, it's a clever phrase.

It wasn't a shooting war, obviously, but fought with words, paper broadsides, angry editorials, that sort of thing.

Rooted in real issues, though, like American deaths after the Panic of 1837.

Definitely.

And also a lot of cultural friction.

British travelers like Francis Trollope would visit America and write these incredibly critical books about American manners, which, you know, didn't go over well.

But there were also some genuinely dangerous moments, particularly on the border.

Oh, absolutely.

Several flashpoints.

You had the Caroline Incident back in 37, an American steamer, the Caroline, was supplying Canadian rebels.

And a British force crossed the border.

Exactly.

Things got tense again a few years later when a Canadian named McLeod was arrested in New York and charged with murder because he'd boasted about being involved.

London basically threatened war if he was executed.

You got acquitted, though, thankfully.

He did.

Then you have the Creel Incident in 1841.

This one really hit a nerve in the South.

Tell us about that.

It involved 130 slaves who rebelled aboard the American ship Creel.

They took control and sailed the Bahamas, which was British territory.

And Britain had abolished slavery.

Right.

So British officials there offered the slaves asylum.

For southern slaveholders, this was horrifying.

It raised the specter of British islands becoming safe havens right off their coast.

You can see how that would escalate fears.

And then there was also trouble up in Maine.

The Euristic War.

Yeah, though war is a strong word.

It was more like a brawl between lumberjacks from Maine and Canada over the disputed border territory.

No one was killed, but it showed how easily things could flare up.

So how did they cool things down with Britain?

Diplomacy, thankfully.

The Webster -Ashburton Treaty of 1842.

Daniel Webster, Tyler's Secretary of State, negotiated it with Lord Ashburton.

And it settled the Maine boundary dispute.

It did.

The U .S.

got about 7 ,000 of the 12 ,000 disputed square miles.

The British got the remaining territory, which importantly included the they needed for a road connecting Halifax and Quebec.

A reasonable compromise.

And there was this interesting little bonus that nobody really realized at the time.

The treaty also adjusted the boundary further west, near Lake Superior.

That adjustment gave the U .S.

about 6 ,500 square miles of land that later turned out to contain the incredible Musabi iron ore range in Minnesota.

Absolutely priceless for America's industrial future.

An accidental jackpot.

Pretty much.

So Britain calmed down, attention turned south to Texas.

The Lone Star Republic, independent since 1836, but Mexico still considered it a rebellious province.

And Mexico made it very clear, annex Texas, and it means war.

But Texas was also becoming a pawn in international games.

Very much so.

Britain and France were interested in keeping Texas independent.

Partly to block American expansion southward.

Undermine the Monroe Doctrine.

Exactly.

And Britain specifically saw an independent Texas as a potential major cotton source, free from reliance on the American south, and maybe even a place to push for abolition right on the border of slaveholding America.

So the pressure to annex Texas is building not just from Americans who want the land, but also because of these foreign interests.

Right.

And this all feeds into this this powerful idea taking hold in the 1840s.

Manifest destiny.

Manifest destiny.

The phrase itself was coined in 1845 by John L.

O.

Sullivan, a journalist.

And what did it mean, really?

It was this belief, this feeling that God had manifestly or obviously destined the American people to spread their democratic institutions across the entire continent.

Maybe even the hemisphere.

A mix of idealism and, well, greed.

Absolutely.

It married this sense of divine mission with very practical desire for land and resources.

And it became incredibly popular.

And completely dominates the election of 1844.

It does.

The Democrats bypass the established figures and nominate James K.

Polk of Tennessee.

He's the first real dark horse candidate.

And this platform?

Pure expansion, re annexation of Texas and reoccupation of Oregon, all the way up to the latitude line, 54 degrees, 40 a minute.

54, 40 or fight.

That was the slogan, right?

That was the rallying cry.

Polk runs against the Whig leader, Henry Clay.

And Polk wins, but it's close.

Very close.

And here's a key bit of political irony.

A third party, the anti -slavery Liberty Party, runs candidates, too.

They strongly oppose annexing Texas because it would expand slavery.

But in New York state, the Liberty Party pulls just enough votes away from Clay, who was seen as slightly less eager for Texas than Polk, that it actually swings the state and therefore the election to Polk.

Wow.

So the party most opposed to Texas annexation actually helped elect the pro annexation candidate.

Exactly.

One of history's little twists.

Polk's narrow victory is then interpreted by the outgoing president, John Tyler, as a clear mandate from the people to annex Texas immediately.

Even though Polk hadn't even taken office yet.

Right.

Tyler knows he can't get the two thirds Senate majority needed for a formal treaty.

So he pushes for annexation via a joint resolution of Congress, which only needs a simple majority in houses.

And it works.

Just three days before leaving office in early 1845, Tyler signs a resolution and Texas is officially invited to join the union.

So Polk enters the White House with Texas already basically secured.

What's his agenda then?

Polk was incredibly methodical, very hardworking, maybe not brilliant, but intensely focused.

He apparently had a clear four point must list for his presidency and remarkably he achieved all four in his single term.

OK, what were they?

First, lower the tariff.

He achieved that with the Walker tariff of 1846, which significantly reduced rates from the 1842 levels down to about 25 percent.

Big win for the South and West.

Number two, restore the independent treasury system, which the Whigs had abolished.

He did that in 1846, putting government funds back into vaults instead of private banks.

Jacksonian principles, basically.

Very much so.

And points three and four were pure expansion.

Settle the Oregon dispute with Britain and acquire California from Mexico.

Let's take Oregon first.

The Democrats campaigned on 54 -40 or fight.

Did Polk stick to that?

Well, the situation on the ground was changing.

By 1846, thousands of American settlers, maybe five thousand or so, had poured into the Oregon country via the Oregon Trail.

They vastly outnumbered the British subjects.

There are maybe only 700, mostly fur traders.

So American presence was much stronger.

Much stronger.

And frankly, once Texas was annexed, some of the urgency, especially from Southern Democrats, to fight for all of Oregon cooled off.

They didn't necessarily want that many potential free states.

And so Polk compromises.

He does.

He backs away from 54 degrees 40 minute.

The British, seeing the writing on the wall with the influx of American settlers, actually come forward and propose extending the existing boundary line along the 49th parallel all the way to the

And Polk accepts.

He puts it to the Senate and they approve the treaty in 1846.

It helped, of course, that by the time the Senate voted, the U .S.

was already about a month into a war with Mexico.

One war at a time seemed prudent.

Right.

So that brings us to California, Polk's other big goal.

Yes.

California, especially the magnificent natural harbor of San Francisco Bay, was seen as the great prize, America's gateway to the Pacific.

Polk was determined to get it.

But Mexico wasn't exactly eager to sell, especially after the Texas annexation.

Not at all.

Relations were terrible.

There were longstanding issues, like Mexico owing about $3 million in damages to U .S.

citizens.

And then there was the huge dispute over the Texas boundary itself.

Texas claimed the Rio Grande River as its southern border.

Right.

But Mexico insisted the boundary had always been the Nueces River, further north.

That left a vast strip of land in dispute.

So Polk tries to buy California first.

He sends an envoy, John Slaydell, to Mexico City in late 1845.

Slaydell is authorized to offer up to $25 million for California and the territory to its east.

And Mexico's response?

The Mexican government, already feeling insulted and pushed around over Texas, refuses to even receive Slaydell officially.

They won't even discuss the offer.

So Polk feels snubbed, diplomatic options exhausted.

What next?

He decides to force the issue.

In January 1846, he orders General Zachary Taylor to march his army of about 4 ,000 troops from the Nueces River southward, deep into that disputed territory between the Nueces and the Rio Grande.

Right up to the Rio Grande, across from Mexican forces.

That sounds like a provocation.

It absolutely was.

Taylor's troops camped there for months, basically daring the Mexicans to respond.

Polk, meanwhile, was getting impatient.

He was apparently ready to ask Congress for a declaration of war based just on the unpaid claims and the Slaydell rejection.

But then something happens.

Yes.

On the evening, Polk was supposedly finalizing his war message, news arrives.

On April 25, 1846, Mexican troops had crossed the Rio Grande and attacked an American patrol.

Sixteen Americans were killed or wounded.

That was the spark Polk needed.

Precisely.

He quickly redrafted his message to Congress, declaring dramatically that Mexico had, quote, invaded our territory and shed American blood upon the American soil.

And Congress bought it.

Overwhelmingly.

Fueled by manifest destiny, excitement and patriotic outrage, Congress voted readily for war.

But not everyone was convinced it was American soil, right?

There was opposition.

Oh, yes.

Significant opposition, especially from Whigs in Congress.

A relatively unknown first term congressman from Illinois, Abraham Lincoln, famously introduced his spot resolutions.

Demanding to know the exact spot where American blood was shed.

Exactly.

Questioning Polk's claim that it was undeniably American soil.

It earned Lincoln the nickname Spotty Lincoln from his critics, but it highlighted the unease many felt about the war's justification.

Anti -slavery groups were also fiercely opposed, calling it Mr.

Polk's War, a conflict designed to grab more land for slavery.

Despite the controversy, how did the war itself go for the U .S.

military?

Remarkably well from a military standpoint.

American forces won essentially every major engagement.

General Stephen Kearney marched west and easily captured Santa Fe in 1846.

And California.

Captain John C.

Fremont was already out there and played a role in the Bear Flag Revolt, where American settlers declared California independent, though that was short lived as U .S.

forces soon took over.

The main fighting was deeper in Mexico, though.

Yes.

General Zachary Taylor, old rough and ready, won several victories in northern Mexico, culminating in the Battle of Buena Vista, where his outnumbered forces repelled a large Mexican army led by Santa Ana.

Taylor became a huge national hero.

But he didn't take Mexico City.

No, that was General Winfield Scott, old fuss and feathers.

He led a daring amphibious landing at Veracruz on the coast and then conducted a brilliant, hard -fought campaign inland, finally capturing the Mexican capital, Mexico City, in September 1847.

Which effectively ended the fighting.

It did.

Now came the challenge of securing the peace treaty.

Polk had sent a State Department cloak, Nicholas Trist, along with Scott's army, to negotiate.

But Polk grew impatient with the negotiations and actually recalled Trist.

Trist, however, disobeyed the recall order.

He saw a window of opportunity to make a deal with the shaky Mexican government and went ahead anyway.

Bold move.

Did it work?

It did.

On February 6, 1848, Trist signed the Treaty of Guadalupe Hidalgo.

And the terms?

What did the U .S.

get?

The U .S.

got confirmation of the Rio Grande boundary for Texas, and Mexico ceded the enormous territory known as the Mexican Session.

This included present -day California, Nevada, Utah, most of Arizona, and New Mexico, and parts of Colorado and Wyoming.

Roughly half of Mexico's territory.

An immense land grab.

And what did the U .S.

give in return?

The U .S.

agreed to pay Mexico $15 million and assumed the $3 .25 million in claims owed by Mexico to American citizens.

So the war achieved Polk's expansionist goals, but it fundamentally changed the map and the power dynamics.

What about the people living in those ceded territories, like the Californios?

Their world was completely upended.

The Californios, the descendants of the original Spanish and Mexican settlers in California, had already seen their influence decline after Mexico secularized the Franciscan missions in the 1830s.

But the American takeover, followed almost immediately by the Gold Rush, just overwhelmed them.

Their land, their culture, their political power.

It was all largely swept away by the flood of Anglo newcomers.

A tragic consequence often overlooked.

What were the broader legacies of this war, according to the chapter?

Well, several major ones.

Militarily, it was like a training ground, a blood -spattered schoolroom for the generation of officers who would lead both sides in the Civil War.

Think Lee, Grant, Sherman, Jackson.

They all got critical experience in Mexico.

And internationally.

It soured relations with Latin America significantly.

The U .S.

started being seen much more warily, feared as the Colossus of the North.

It created a legacy of mistrust that lasted a long time.

But the most significant consequence, the one that ties back to the beginning.

Slavery.

The expansion itself carried this terrible moral burden.

Ralph Waldo Emerson warned prophetically, Mexico will poison us.

And the poison was the question of whether slavery would expand into these newly acquired territories.

Precisely.

The issue exploded almost immediately.

Even before the war ended in 1846,

a Pennsylvania congressman named David Wilmot introduced an amendment to a funding bill.

The Wilmot Proviso.

Yes.

It stipulated that slavery should never exist in any territory acquired from Mexico.

Did it pass?

It passed the House, where the North had more population and thus more votes, twice.

But it failed in the Senate, where the South had equal representation.

So it never became law.

But its impact was huge anyway.

Immense.

The Wilmot Proviso became the symbol of the intense, unavoidable conflict over slavery's expansion.

It ripped open the sectional divide wider than ever before.

It showed that the North was increasingly determined to halt slavery's spread, and the South was equally determined to defend its right to expand.

So looking back at this whole period, 1841 to 1848, we go from Tyler's unexpected presidency and squabbles with Britain.

Through this fever pitch of manifest destiny under Polk, the Oregon settlement, the war with Mexico.

Ending with this vast new territory, but also this deadly argument about what to do with it regarding slavery.

Exactly.

The chapter really drives home that connection.

John C.

Calhoun, the fierce defender of Southern rights, saw it coming.

He warned that Mexico was like forbidden fruit, and eating it would subject American institutions to political death.

The new land acquired through manifest destiny and war became the source of the conflict that would nearly destroy the nation.

Santa Ana's revenge, as the chapter puts it.

A powerful thought.

It really makes you consider how a seemingly unifying national project expansion could so quickly fracture the country along that single terrible fault line of slavery.

A crucial and sobering period to understand.

Thank you for walking us through it.

My pleasure.

And thank you for joining us for this deep dive.