The United States has never delayed a presidential election. But there was one instance in which some wondered if the country should: when the nation was embroiled in the Civil War.

The 1864 election was the second U.S. presidential election to take place during wartime (the first was during the War of 1812). Still, it wasn’t the logistics of carrying out a wartime election that made some people want to postpone it. Rather, it was the fact that by the spring of 1864, the Union had no clear path to victory, and many feared President Abraham Lincoln wouldn’t win reelection.

Today, conventional wisdom holds that incumbent presidential candidates are more likely to win reelection, especially during wartime. Franklin Delano Roosevelt won an unprecedented fourth term during World War II, and Richard Nixon delayed Vietnam peace talks because he thought prolonging the Vietnam War would help his reelection chances in 1972 (and indeed, he won a second term). Yet in 1864, this wasn’t a common assumption—the eight presidents directly preceding Lincoln had each served one term or less.

Lincoln’s main weakness as a candidate was that the Union’s war against the Confederacy wasn’t going well. By the spring of 1864, the Civil War had been going on for three years with no end in sight, and many voters (i.e., white men ages 21 and up) were starting to get war-weary. Lincoln agreed with his advisors that his chances for winning reelection looked grim, but he disagreed with those who suggested he delay the election.

“Lincoln always felt that the Civil War was, number one, about democracy,” says Eric Foner, a professor emeritus of history at Columbia University and author of The Second Founding: How the Civil War and Reconstruction Remade the Constitution.

“[Lincoln thought] if you suspend democracy in the middle of the war, you are basically undercutting the whole purpose of the war,” he continues. “So even when he thought he was going to lose, he never really contemplated suspending the presidential election.” (Lincoln did, however, suspend the writ of habeas corpus and ignore a ruling by the Supreme Court’s chief justice that he didn’t have the authority to do so.)

When Lincoln first ran for president in 1860, it was his Republican Party that had a stronghold in the north, and the Democratic Party that had found popularity in the south. When 11 southern states seceded to join the Confederacy, the Republican Party became the Union’s dominant political party. Even so, for the 1864 election, the Republican Party decided to join forces with some Democrats to form the National Union Party.

Despite concerns about Lincoln’s electability, the National Union backed him as its presidential candidate. Yet notably, Lincoln ditched his current Republican vice president to run with Andrew Johnson, a Democrat who had previously supported slavery, in an attempt to “balance the ticket.”

Meanwhile, a divided Democratic Party nominated George McClellan, a popular general who’d served in the Union Army. Lincoln’s campaign position was that there would be no ceasefire until the south rejoined the north and ended slavery. In contrast, McClellan said his only condition for ending the war would be that the Confederate states rejoined the Union.

Whether or not slavery continued—as well as the fate of black Americans—was not a priority for McClellan or the Democratic Party. And in the party’s attempt to win the votes of war-weary white northerners, it launched “probably the most racist presidential campaign in American history,” says David Goldfield, a history professor at the University of North Carolina at Charlotte and author of America Aflame: How the Civil War Created a Nation.

For example, one Democratic political cartoon exploited white Americans’ fears about interracial sex by depicting a fictional “Miscegenation Ball at the Headquarters of the Lincoln Central Campaign Club.” Another Democratic campaign pamphlet referred to Lincoln as “Abraham Africanus the First” and declared that the first commandment of the Republican Party was “Thou shalt have no other God but the negro.”

Ultimately, what helped Lincoln win over McClellan wasn’t the fact that he wanted to end slavery. It was the fact that in the two months before the election, the Union achieved major military victories by capturing Atlanta and winning a major battle in the Shenandoah Valley. These military victories boosted morale among both civilian and military voters. Soldiers in particular seemed to agree with Lincoln’s campaign slogan: “Don’t change horses in the middle of a stream.”

In order to pull off the 1864 election, the Union needed a way for soldiers stationed far from their homes to vote. To this end, most northern states passed new laws allowing soldiers to cast absentee votes from military camps. However, because soldiers were more likely to vote for their current commander-in-chief, there were some partisan attempts to suppress their votes.

“In states where the Democrats controlled the state legislature, like Indiana, they did not allow soldiers to vote in their army camps,” Foner says. “But the War Department kind of encouraged commanders to let these soldiers go home for a week or something in order that they could vote.”

The election also included three new states: Kansas, West Virginia and Nevada. Kansas had joined the Union as a free state in 1861, just after Lincoln’s first presidential election and before the Civil War started. West Virginia joined in 1863 after breaking off from the Confederate state of Virginia. And Nevada actually became a state on October 31, 1864, just a week before the election, in part because Congress thought it might give Lincoln an electoral edge, Foner says.

On November 8, Lincoln won in a landslide. He received 54 percent of the civilian vote, 78 percent of the military vote and 212 electoral votes across 22 states. In comparison, McClellan took 21 electoral votes in only three states: Delaware, Kentucky and his home state of New Jersey. The victory meant Lincoln continued leading the war with the goal of reuniting the country and abolishing slavery.

“I think it was one of the most critical elections in our history,” says John C. Waugh, a historical reporter and author of Reelecting Lincoln: The Battle for the 1864 Presidency. “And thank god that Lincoln won.”