March 6, 1820

President James Monroe signs the Missouri Compromise

The Missouri Compromise resolved the worries of both Northern and Southern states who feared losing their precious influence in Congress. When Missouri was set to enter the U.S. as a slave state, northern states said "um, no."

The result was an imaginary line drawn at what's known as the 36th parallel across America. Above the line: no slavery allowed. Below the line: slavery allowed.

Oh, and Maine became a (non-slave) state too. Get it, Pine Tree State.

August 22-23, 1831

Nat Turner Slave Rebellion

For all the paranoia about slave rebellions that southern slaveholders had, this is one of the very, very few significant ones that actually happened. It was a pretty grisly affair too.

Nat Turner, a Virginia slave by birth, started having visions and seeing signs that the time had come to rise up against the slave masters. Over the course of about a day, he led a group of up to forty slaves in a rampage that killed at least fifty-five white people living in local houses.

Virginia nearly abolished slavery afterwards, but decided to keep it and just, you know, be harsher instead. (Source)

1846-1848

Mexican-American War

Alternate title: How the West Was Won.

The Mexican-American War is a bit of a long story, and it was the result of a few decades of changing relationships with Mexico. Essentially it was a border dispute that went horribly awry and ended up with the U.S. taking about half of Mexico's territory in the Treaty of Guadalupe Hidalgo.

This opened up the whole debate about slavery as people and politicians argued over where slavery would extend in all this new land.

January 29, 1850

Introduction of the Compromise of 1850

So, America had all this new land that used to be Mexico, which eventually had to be organized into states. How do you do that without upsetting the balance of power in Congress between slave-holding states and free states?

Great question.

Enter Henry Clay, the "Great Negotiator," who (aided by Mr. Stephen A. Douglas), came up with a compromise that, in theory, allowed California to enter as a free state as requested, without the southern slave states getting too upset.

In reality, although the compromise answered the issue at hand, no one was really happy with it in the end, and the Fugitive Slave Act that came with it pushed northerners further towards total abolition.

May 30, 1854

Passage of the Kansas-Nebraska Act

The Kansas-Nebraska Act is the Hangover Part 2 of legislation: same basic plot as the previous one, but with darker, less enjoyable results. The question of how to handle the expansion of slavery into the western U.S. had not been magically resolved through the Compromise of 1850, and the nation was once again at a crossroads when trying to incorporate territory directly adjacent to existing states.

Stephen Douglas (of Lincoln-Douglas Debates fame) championed his strategy of "popular sovereignty," which left the decision up to the voters living in that territory. Power to the people, right?

Oh, by the way, this Act cancelled out the Missouri Compromise of 1820 by potentially allowing slavery in a state that was above the 36th parallel.

June 17, 1856

Formation of the Republican Party

The Republican Party—which is vastly different from today's—was originally formed by former Whigs and Democrats who were extremely dissatisfied with the debates and compromises over slavery. Although they started getting together in 1854, this date was their first official nominating convention, and their first real appearance in the American political system.

May 21-24, 1856

"Bleeding Kansas"

Despite what you probably think, this is not a horror movie set in a steakhouse in Lawrence. But it's almost as gruesome.

Once the Kansas-Nebraska Act was passed, the time came for both states to elect delegates to write their new state constitutions. These would be the people who decided whether or not to allow slavery to exist there.

Kansas was leaning towards forbidding slavery, until hordes of "border ruffians" from other states flooded into to vote in the Kansas election. In case you're wondering, this wasn't legal.

Things became super-messy, with multiple governments and constitutions, and eventually violence broke out with the Sack of Lawrence by the ruffians, and the retaliatory Pottawattamie Creek massacre. The term "Bleeding Kansas" wasn't much of an exaggeration, let's put it that way. (Source).

The battleground in Kansas epitomized the state of antagonism over slavery in the antebellum period.

March 6, 1857

Dred Scott Decision

Supreme Court cases are almost always really significant, since you have to hit a pretty high bar to make in front of the federal Supreme Court in the first place. (They're not going to decide whether your neighbor's overgrown hedge is intruding on your yard.)

Dred Scott v. Sandford, though, is one of the most notorious Supreme Court decisions of all time. For an exhaustive description of the ins and outs, look here.

In a nutshell, a slave named Dred Scott had reason to believe he should be freed, as his former master had taken him to live in free states for a number of years. The Supreme Court decided that he wasn't a citizen, and therefore didn't have the right to bring the case in the first place.

Chief Justice Roger Taney then surprised the nation by going a step further, claiming that the Missouri Compromise and all congressional legislation regulating slavery was unconstitutional. You know, to really hammer home the point that Dred Scott was definitely still a slave. Taney made it so Congress could not legally decide whether or not slavery could exist.

The case had become a national sensation, and the decision caused lots of outrage in the North.

December 21, 1857 – August 2, 1858

The Lecompton Constitution

Like Dorothy, we've returned to Kansas.

After all the violence of "Bleeding Kansas," the first constitution that was passed in Kansas was basically totally written and supported by proslavery residents of nearby states. Everyone knew, too, it wasn't some well-kept secret that was dramatically revealed a few years ago in a Ken Burns documentary.

The constitution, which had provisions to protect slavery, was rejected (twice) during elections in the territory. During the process, though, there was a lot of debate in Congress about whether to support it (as President Buchanan did) or not. Even Stephen Douglas, the author popular sovereignty, was against it.

June 16, 1858

"House Divided" Speech at Republican Convention in Springfield, IL

Here we are! While folks in Kansas were sorting themselves out and everyone was reeling from Dred Scott v. Sandford, an up-and-coming politician in Illinois called Abraham Lincoln got on stage to accept the nomination for U.S. Senator for the recently formed Republican party. He lost that battle, but won the war. (Literally, but not until later.)

Anyway, he directly addressed the last few years' worth of insanity over slavery.

August 21 – October 15, 1858

Lincoln-Douglas Debates

Once Lincoln was in the senatorial race, he and his opponent Stephen A. Douglas (Democrat) embarked on a series of seven debates as part of the campaign. Even though it was an Illinois senatorial election, the debates became national entertainment (remember, this is pre-Netflix).

Lincoln tried to emphasize the problems with Douglas' idea of popular sovereignty and slavery in general. Douglas, in turn, tried to paint Lincoln as a raving abolitionist who wanted to destroy the whole system. At this point, being super gung-ho about abolition wasn't seen as a good thing, and Douglas ended up winning the election.

November 6, 1860

Abraham Lincoln elected President of the United States

You probably knew about this one.

What's notable about this election in political history, though, is how sectional it was. There were four candidates from different parties, and Lincoln won by carrying the North. He wasn't even on the ballot in a bunch of southern states. His election was the final straw that motivated some southern states to begin discussing secession (here's looking at you, South Carolina).

April 12, 1861 – April 14, 1861

Battle of Fort Sumter (Charleston, SC)

When federal troops refused to leave Fort Sumter after South Carolina seceded, the action resulted an attack on the fort and the eventual surrender of the U.S. troops. The battle is considered the beginning of the Civil War. That whole "house divided cannot stand" idea was proved right pretty quickly, it seems.

April 12, 1861 – April 9, 1865

The Civil War

Well, you really can't sum up the American Civil War in a few sentences. But we'll try.

All those decades of sectional tension got worse and worse until one large section said, "So long, and thanks for all the fish," and the other said, "Where do you think you're going?"

At the end, slavery was prohibited nationwide, Black men could vote, and all those stressful debates of the antebellum period dissolved into stressful postwar debates.