Sergeant Alvin York was once described as World War I’s “greatest civilian soldier,” yet he began the conflict as a conscientious objector. A deeply devout man from the small mountain town of Pall Mall, Tennessee, York initially resisted serving on the grounds that violence was against his religion. His request was denied, however, and in May 1918 he arrived in France along with the 82nd Division of the U.S. Army.

York would make his name on October 8, 1918, in a famous incident during the Meuse-Argonne offensive. He and around 17 other Americans had just captured troops from a German regiment when they found themselves under heavy fire from enemy machine guns. Nine of the Americans were quickly wounded or killed, but York—a crack shot from his days as a turkey hunter—escaped unscathed and began picking off the German gunners with his rifle. When six of the enemy tried to charge York with bayonets, he drew his .45 pistol and shot them all. He soon forced the remaining Germans to surrender, and later claimed even more prisoners on his way back to the American lines.

Renegade pilot Frank Luke was America’s greatest “balloon buster,” the nickname assigned to the brash aviators who attacked German observation balloons used to sight artillery. Luke joined the 27th Aero Squadron in France in July 1918 and wasted little time in aggravating his fellow pilots with his cocky attitude and reckless flying style. Nevertheless, the Arizona-born aviator proved an expert at downing the reconnaissance balloons—dangerous targets that were often guarded by anti-aircraft guns, cannons and enemy fighters. He scored his first kill on September 12, and by September 28 he had claimed 15 victories, including one day in which he shot down two balloons and three enemy planes.

Despite his obvious skill, the headstrong Luke often flouted military regulations and disobeyed orders. His commanding officer tried to ground him on September 29, but Luke ignored the command and took off on a daring solo balloon-busting mission near Murvaux, France. He proceeded to destroy three balloons in quick succession but was seriously wounded by machine gun fire and forced to ditch his plane near a creek. After climbing from the wreckage, Luke drew his pistol and may have exchanged a few shots with German troops before succumbing to his injuries. By then, the 21-year-old had claimed a remarkable 18 aerial victories in the span of only 18 days. He later became the first-ever pilot to receive the Medal of Honor.

Henry Johnson was the most famous member of the “Harlem Hellfighters,” an all-black National Guard unit that was among the first American forces to arrive in Europe during World War I. Johnson and his fellow African American soldiers spent their early days in the war performing unskilled manual labor before being sent to reinforce the depleted ranks of the French army.

On May 14, 1918, Johnson and another “Hellfighter” named Needham Roberts were serving sentry duty in the Argonne Forest. Just after 2 a.m., the duo was attacked by a detachment of some 20 German troops. Both men had soon been wounded—Roberts so severely that he was unable to stand or shoot—but Johnson held fast and fought back with hand grenades and his rifle. Despite being shot several times, he returned fire until his weapon jammed and then used it as a club and fought hand to hand until it broke into pieces.

When Johnson saw that the Germans were trying to take Roberts prisoner, he drew his one remaining weapon—a bolo knife—and slashed and stabbed several men until the raiding party finally fell back. When the dust cleared, Johnson had inflicted at least a dozen casualties on the Germans and suffered 21 wounds from gunfire and bayonets. Both he and Roberts were later given the Croix de Guerre—one of France’s highest military honors—but Johnson’s heroic stand went unrewarded in the United States until 1996 when he was posthumously awarded the Purple Heart. He later received the Distinguished Service Cross in 2003.

An attorney by trade, Major Charles Whittlesey later made his name as the uncompromising commander of the so-called “Lost Battalion,” an American unit that became stuck behind German lines. On October 2, 1918, the bookish and bespectacled Whittlesey led his men into hostile territory as part of a coordinated offensive in the Argonne Forest. But due to poor communication, his unit crossed the rough terrain too swiftly and was soon cut off and enveloped by German forces.

Whittlesey’s nearly 600-strong force dug in and established a makeshift defensive line. Despite being low on food, water and ammunition, they spent the next five days dodging sniper fire and repelling wave after wave of German attacks. At one point, their own troops began accidentally shelling their position, but Whittlesey launched a carrier pigeon and managed to stop the barrage of friendly fire. The Americans were later offered a chance to surrender, but Whittlesey held his ground and fought on against increasingly grim odds.

Allied reinforcements finally arrived and forced the enemy to retreat on October 8. By then, only 194 of the Americans were still standing, among them Whittlesey, who was later awarded the Medal of Honor for his extreme bravery and coolness under fire. Sadly, Whittlesey remained haunted by the war for the rest of his life, and later committed suicide in 1921 by throwing himself off a ship as it sailed toward Cuba.

Navy officer Edouard Izac’s remarkable odyssey began on May 31, 1918, when a German submarine torpedoed his ship, the USS President Lincoln, as it sailed near the coast of France. Most of the crew managed to escape, but Izac was captured and taken aboard the U-boat for the journey back to Germany. Unbeknownst to his captors, Izac was the son of German-speaking immigrants, and he used his knowledge of the language to collect vital information on German submarine operations.

Determined to get this intelligence to the Allies, Izac later made several failed escape attempts, including once diving out the window of a moving train. He finally pulled off a successful jailbreak in October 1918, when he scaled the barbed wire fence of his prison camp, stopping along the way to draw fire from the guards to allow other prisoners to flee. Izac spent the next several days sneaking through hostile territory and living off the land before swimming the Rhine River into the safety of neutral Switzerland. Though his information ultimately proved of little use so late in the war, he was awarded the Medal of Honor in 1920 and went on to serve several years in Congress. At the time of his death in 1990, he was the last surviving Medal of Honor recipient from World War I.

Marine Sergeant Dan Daly entered World War I as one of the United States’ most famous Marines, having already won the Medal of Honor on two separate occasions for his service during the Boxer Rebellion and the U.S. occupation of Haiti. The 44-year-old continued to write his name into the history books during June 1918’s Battle of Belleau Wood, a month-long offensive that was one of the first major World War I battles fought by U.S. troops. On June 5, Daly bravely extinguished a fire on the verge of igniting a cache of explosive ammunition. Two days later, as his Marines were being shredded by enemy machine gun fire, Daly urged them to leave their cover and counterattack by supposedly screaming the famous words, “Come on, you sons of bitches! Do you want to live forever?!”

Daly’s near-suicidal courage was put on display once again on June 10, when he singlehandedly charged a German machine gun nest, killing its commander and taking 14 prisoners. That same day, he made several trips into “no man’s land” to drag wounded troops to safety. Daley was wounded later that month during a second solo rescue mission, and suffered two more injuries during the Meuse-Argonne offensive in October 1918. While he was again recommended for the Medal of Honor for his actions at Belleau Wood, the military balked at the prospect of any soldier receiving the award three times, and he was instead given the Distinguished Service Cross and the French Medaille Militaire. General Smedley Butler—himself a double Medal of Honor winner—would later describe Daly as, “the fightingest Marine I ever knew.”