antebellum

Technically, this means "pre-war." But the majority of the time you'll hear it is in reference to the "antebellum period," which is what we call the decades immediately prior to the Civil War.

The most common usage is in talking about the 1850s, but there's no clear decision on when it starts. It generally includes the events that contribute to the outbreak of the Civil War, and it's sometimes stretched to go back several decades.

Missouri Compromise

In 1819, when Missouri wanted to enter the United States as a slave state, the northern states got all up in arms because it would upset the balance of slave/non-slave states in the Senate.

And upsetting that balance was a big no-no.

Congress resolved it through two stipulations: first, Maine would enter the union as a free state, and second, a geographic line would be drawn across the middle of the country. North of latitude 36°30′ (known as the 36th parallel), slavery would be forbidden. South of the line, you could own as many human beings as you pleased because history is dark and full of terrors.

Mexican-American War

Americans in Texas had long had issues with Mexico. Texans had already fought them to become an independent republic back in 1836, and no one had ever totally agreed on where the southern border of Texas actually was. (The just agreed that it was where you could eat delicious steaks on the cheap.)

Once Texas was finally annexed in 1846, the tension boiled over after a group of American soldiers crossed the Rio Grande into what Mexico considered to be…Mexico. President Polk took the opportunity to declare war, winning half of Mexican land in the Treaty of Guadalupe Hidalgo.

The war was pretty much only supported in the South, because they were hoping for more southern (slaveholding) territory. Northerners like Lincoln were generally not on board.

Compromise of 1850

Once the U.S. got tons and tons of new land after the Mexican-American War, people immediately started moving in. California got a population boost in 1849 with the Gold Rush, and when the time came to become a state, they said: "no slavery, please."

Being a very long state, California exists on both sides of the line established by the Missouri Compromise, so Congress had to figure out how to handle the request and somehow make everyone mildly happy. ("Mildly happy" in this historical context vaguely translates to "not getting stabby.")

The result was a compromise in which: (1) California becomes a free state, (2) slavery in the Utah and New Mexico territories would be left up to the citizens, (3) New Mexico gets land disputed between them and Texas, (4) the slave trade (but not slavery) was abolished in Washington, D.C., and (5) a stronger Fugitive Slave Law was enacted.

Free Soilers

As America really started to expand westward (regardless of who was already living there, naturally), there was constant tension and debate over where to allow slavery.

Most southerners wanted to expand it to as much western territory as possible, abolitionists wanted it gone complete, and Free Soilers wanted to just prevent slavery in any new states. Really, they mostly were against slavery but didn't think full emancipation was realistic, so they fought to prevent the institution's expansion. Abraham Lincoln was one of these guys.

tenon

A tenon is the part of a piece of wood (like a beam, or a timber…maybe a repurposed Nimbus 2000) that sticks out at the end, so it can be put into the matching mortise and join two bits of wood together, snug as a bug in a rug. Lincoln uses this term when he leans into the "house" metaphor.

mortise

The mortise is an opening or indentation in a piece of wood that is designed to match the tenon of another piece. Then the two can be joined together, and we can all live happily ever after.

Squatter sovereignty

Lincoln uses this term to refer to what we call "popular sovereignty." A.k.a. when residents of a soon-to-be state decide for themselves whether or not to allow slavery, instead of Congress making the decision.

"Popular" is a bit of a nicer term, isn't it?

Nebraska Bill

This is what Lincoln calls the Kansas-Nebraska Act. The Kansas-Nebraska Act of 1854 organized the Kansas and Nebraska territories into states, where the presence of slavery would be determined via popular (or "squatter") sovereignty.

It, um, didn't go well, which is why Lincoln brings it up a number of times in his speech.

Silliman letter

While Kansas attempted to sort itself out and create a constitution in 1857, the governor Robert J. Walker brought in federal troops in August of that year to control the people of Lawrence, Kansas, who he claimed were the ones causing all the fuss and violence.

You can imagine how popular something like that was.

In response, a group of forty-three distinguished men in Connecticut, led by Benjamin Silliman of Yale University, wrote a letter to President James Buchanan condemning the use of military force against American citizens. The letter was published in newspapers, and the president quickly responded, saying the troops were needed to stop those pesky free-state agitators trying to go against the recent Supreme Court ruling and ban slavery in the state.

Maybe you can guess what side of the slavery debate Buchanan fell on. Hint: not the same as Lincoln.

Lecompton Constitution

After Kansas exploded (almost literally) while attempting to vote on the delegates to write their constitution, a couple rival governments were set up. The one that technically held power thanks to the (relatively fraudulent) vote was based in Lecompton, and wrote this constitution in December 1857 that protected slavery in the state.

Even Stephen Douglas, who created the idea of popular sovereignty, wasn't cool with this constitution. It didn't pass, but it was a big talking point given the crazy-high tension over the slavery question and the recent events in Kansas.

Dred Scott decision

The decision issued by the Supreme Court on March 6, 1857, dismissed Dred Scott's suit for freedom from his status as a slave, and took the opportunity to declare that Congress could not constitutionally regulate slavery.

All in all, it was a nasty little decision.

Dred Scott had sued for freedom because he'd been held by his master in free states for a number of years. Chief Justice Roger Taney said they couldn't decide the case, because Black people weren't citizens of the United States. (Apparently, he knew exactly what the Founding Fathers were thinking, and they totally didn't mean for Black people to ever be citizens.)

Then Taney, for some reason no one's quite figured out, said that the Missouri Compromise that had made those states non-slave states was unconstitutional, as was any attempt by Congress to say yay or nay to slavery.