IB History: The American Civil War — notes, maps and essay questions

Chapter 1: Manifest Destiny and the Mexican War

Land hunger and an ideology of destiny. Americans were moving west faster than their government could follow, so Washington came under pressure to secure land its citizens had already entered. Thousands took the Oregon Trail in the 1840s, the brown arrow on the map. Expansionists dressed this movement in the language of Manifest Destiny, the belief that Providence had given the continent to the United States. The idea joined real hopes, such as Pacific ports for the China trade, to a racial conviction that Mexicans and Native peoples should give way.

Polk’s determination to have California. The most direct cause was a president who wanted California badly enough to take it. Polk entered office in 1845 with a short list of goals, and California, with its harbours at San Francisco and San Diego, stood near the top. He first tried to buy it, sending John Slidell to Mexico City authorised to offer up to $25 million by most accounts, and the Mexican government refused to receive him. Polk then moved Taylor’s army to the Rio Grande, into land that Mexico held and Texas claimed, which turned a diplomatic refusal into an armed standoff.

A Mexican state at its weakest. Mexico in 1846 was in no condition to fight a long war. Its treasury was empty, its army was led by generals who also made and unmade governments, and its northern states had been devastated by Comanche and Kiowa raids. Mexican leaders could not sell territory without being overthrown, as Herrera discovered when Paredes toppled him for being willing to talk. Weakness made war more likely, because it left Mexico able neither to deter Polk nor to bargain with him.

Texas and the politics of slavery. Texas joined the Union as a slave state, and its annexation was argued in the language of slavery from the start. In 1844 Secretary of State Calhoun told the British minister that annexation would protect slavery from British abolitionism, and the Senate rejected the treaty that June partly for that reason. When annexation passed by joint resolution in 1845, Northern opponents saw the “slave power,” the slaveholders’ supposed grip on the federal government, enlarging itself. The war inherited that suspicion, which is why Northern congressmen moved at once to keep slavery out of its conquests.

Chapter 2: A House Dividing

Slavery as capital, not merely labor. Emancipation somewhere threatened property values everywhere: an enslaved person in Virginia was worth more because Mississippi and the territories were open markets. That is why the South fought over distant Kansas. Closing the frontier didn’t just limit slavery, it started the clock on its financial collapse. Follow the money and the politics of 1850–60 stop looking irrational.

Two economies, two civilizations. The free states built factories, railroads, public schools and cities of immigrants. The South built the world’s most profitable plantation economy on bound labor. Each section believed the other was betraying the Founders. The tariff, homesteads, railroads. Every national question became a proxy for the one question underneath.

The machinery of compromise breaks. Compromise had worked when both sections could win something. Kansas–Nebraska destroyed the one fixed rule (the 36°30′ line). Dred Scott destroyed the possibility of any new rule. And the caning of Senator Sumner on the Senate floor (1856) showed that even the forum itself was failing. Institutions do not usually die at once. They die rule by rule.

The sectional math of 1860. Free-state population had grown until it could elect a president alone. Lincoln carried every northern state and lost every slave state. The first purely sectional victory in American history. The South’s choice was now to live as a permanent political minority inside the Union, or to leave it. Secession was, among other things, a refusal to lose an election.

Chapter 3: Secession Winter

A four-month vacuum of power. The Constitution then left presidents-elect waiting until March. Buchanan held that secession was illegal but that coercion was also illegal. A doctrine of perfect paralysis. Into that vacuum the Deep South organized a government, seized arsenals and forts, and made secession a fact before anyone in Washington could contest it. Institutional dead time is when revolutions happen.

The secessionists’ own words. The ordinances and declarations are primary sources without ambiguity: Mississippi. “our position is thoroughly identified with the institution of slavery, the greatest material interest of the world.” Alexander Stephens, the Confederacy’s vice-president, called slavery the “cornerstone” of the new state. Later generations rewrote the cause. The founders of the Confederacy did not.

Sumter as a designed dilemma. Lincoln’s resupply announcement transferred the decision to Charleston: fire on food, or watch the fort stand. Davis chose war partly because the Confederacy needed the upper South and believed a fight would bring it in. Which it did, at the price of making the Confederacy the aggressor in Northern eyes and uniting a divided North overnight. Both presidents got the war they expected. Only one got the opening he wanted.

Why the border stayed. Lincoln suspended habeas corpus in Maryland, tolerated a rump legislature in Missouri, and famously kept hands off Kentucky’s declared “neutrality” until the Confederacy blundered first by occupying Columbus. “I hope to have God on my side,” he is said to have remarked, “but I must have Kentucky”. With it came the Ohio River line, Missouri’s rivers, and 400,000 white men of military age plus, later, tens of thousands of Black recruits.

What stayed settled. No state has attempted secession since. The Thirteenth Amendment has never been seriously challenged. “the Union” stopped being a debating point and became the weather. Constitutional questions truly closed by force are rare in history. This atlas shows the price of closing one.

What stayed open. Citizenship’s content. The vote, the school, the jury, the deed. Remained contested from Colfax to Selma along precisely the lines this map drew. Read any twentieth-century civil-rights map beside this one: the geography rhymes, county by county. That planned atlas is this one’s sequel in spirit.