The 1989 film Glory indelibly associated African American soldiers in the Civil War with the Battle of Fort Wagner. In that battle in July 1863, the 54th Massachusetts Volunteer Infantry of former slaves and free black Americans stormed a fort near Charleston, S.C. sustaining heavy losses and proving that black men would give their lives for the Union. Far less famous but no less important, though, was the Battle of Olustee, fought on February 20, 1864. It was the largest Civil War battle fought in Florida, and it was crucial in cementing black freedom.

By 1864, the Union had a number of reasons to want to carve Florida away from the rest of the Confederacy. Isolating the state would do a number of things for the Union cause. First of all, southerners both in the army camps and on the homefront desperately needed food, especially meat. The Union had separated the Texas cattle herds from the rest of the South when it took the Mississippi River in 1863, and the beef produced in Georgia, Alabama, North Carolina, and South Carolina could not make up the loss. Florida also produced meat, though, sending about 20,000 head of cattle and 10,000 hogs a year to the southern armies. If the Union could cut the lines between Florida and the rest of the South, it would be closer to starving the South into submission.

There were political reasons to capture Florida, too. President Lincoln wanted to reorganize Florida as a Union state out from under the Confederacy much as he was trying to do in Louisiana. Opponents carped that he was trying to get Florida back into Congress so he could count on more electoral votes in the 1864 election, and this was probably true. The beleaguered president was facing an insurgency from within his cabinet, and more electoral votes in his column could help his reelection. But there were obvious reasons to want Florida back on the Union side even without the president’s reelection fight looming on the horizon. Chipping away at the edges of the Confederacy would hasten the end of the war.

Finally, an excursion into Florida promised to attract black recruits to fight for the Union. By 1864, battles and disease had thinned the Union ranks, and new volunteers would be most welcome.

On February 7, 1864, Federal troops landed in Jacksonville, where they found the countryside largely deserted. Nonetheless, Brigadier General Truman Seymour, the head of the expedition, had strict orders not to move far from Jacksonville. Instead, Union troops under Colonel Guy V. Henry of the Fortieth Massachusetts mounted quick raids that destroyed supplies and reconnoitered the Confederate army. Their operations among the poor and dispirited people were successful and relatively painless: they suffered few losses.

It was perhaps the ease of the raiding to that date that made General Seymour decide on February 17 to march his 5,500 men 100 miles west to destroy the railroad bridge over the Suwanee River. Seymour did not know that Confederate officers had figured out that Florida was in danger and had moved troops quickly to prevent Union soldiers from gaining a foothold in the interior. Five thousand Confederates under Brigadier General Joseph Finegan were encamped on the road Seymour’s men would take, near the railroad station at Olustee, about fifty miles from Jacksonville.

When the two armies came together in mid-afternoon on February 20, Seymour threw his men in without much forethought, apparently believing he was up against the same ragtag fighters Henry had been smashing for weeks. But Finegan’s men were experienced troops. They held their ground, firing relentlessly on the white Union soldiers and African American soldiers from the 8th U.S. Colored Troops. As the Confederates advanced in mid-afternoon, cutting deep into the Union troops, Seymour realized he had to pull his men out. To cover the retreat, he threw his reserves into the battle. These reserves consisted of soldiers from the Massachusetts 54th and the 35th United States Colored Troops. One white soldier later noted: “The colored troops went in grandly, and they fought like devils.” The black soldiers held their ground until past dark, enabling their comrades to get safely out of range, before they received orders to move back toward Jacksonville.

The black soldiers at Olustee paid dearly for their heroism. The casualties at the battle were high on both sides: the Federals lost more than 1800 men, nearly one out of every three men, while the Confederacy lost 950, or about one out of every five. But black Union soldiers bore a special burden. The Union troops knew that Confederates furious at the idea of emancipation would give no quarter to black soldiers, and white and black soldiers both tried valiantly to make sure no one was left behind. But they didn’t save everyone. Confederate soldiers shot and clubbed to death as many as fifty wounded black soldiers before the men could be rescued.

The Union would not attempt to control Florida again, although it would maintain a foothold at Jacksonville and launch raids from there for the rest of the war. But while it did not do much to change the course of the war, Florida’s major Civil War battle changed the course of American history by making a searing impression on President Lincoln. Advisers had suggested that he help boost his chances for reelection by backing off on emancipation to court conservative voters. But President Lincoln would have none of it. “There have been men who have proposed to me to return to slavery the black warriors of… Olustee to their masters to conciliate the South,” he told visitors in August 1864. “I should be damned in time & in eternity for so doing.”