Future-President Harry S. Truman was a hero in World War I who technically broke orders when, as a captain, he ordered his men to fire out of sector during the Meuse-Argonne Offensive, eliminating German artillery batteries and observers in order to protect U.S. troops. But his first battle saw his men break ranks until Truman, shaking from fear, rallied them back to their guns.
The fight came in the Vosges Mountains in eastern France. Truman had recently been promoted to captain and given command of Battery D, 129th Field Artillery Regiment. His battery was known as a smart, athletic, but undisciplined lot. He managed to wrangle influence over them.
But he was still untested in battle when his battery moved into position Aug. 29, 1918, and began their bombardment of German positions. The battery's four 75mm guns sent rounds downrange, and it was great—at first. As Pvt. Vere Leigh later said, "We were firing away and having a hell of a good time doing it until they began to fire back."
Truman had been in command for less than two months, and his men began to melt away under the cover of rain and darkness. Rumors that the German shells contained gas agents sent the men scrambling to get masks on themselves and their horses.
In all this chaos, it was easy for the artillerymen, especially the support troops, to run into the woods and rocks of the area. Truman was afraid himself and had to struggle to remain in place. He would later write to his wife, "My greatest satisfaction is that my legs didn't succeed in carrying me away, although they were very anxious to do it."
Truman was on his horse, trying to keep his unit organized and in place until he rode into a shell crater and tumbled with his horse to the ground. A soldier had to help get him out from under the horse, and Truman watched the fleeing men around him and had to decide whether to run as well.
But he did hold position, and he began insulting and cajoling his troops to get them back on the guns. "I got up and called them everything I knew," he said. The language was surprising coming from the relatively small and bespectacled captain, but it worked. Gun crews began shifting back to their weapons, other troops got horses back in line in case the battery needed to move, and American rounds screeched through the air to thunder home in German positions.
Most of his men, of course, refused to admit if they ran. So the men began referring to it as the "Battle of Who Ran."
Truman's poise under fire helped endear him to the men, even if he had secretly been terrified. This would later help them stick together in the Meuse-Argonne Offensive when Truman ordered them to kill German artillery batteries and observers that were technically out of the division's sector. Truman got in trouble for firing out of sector, but he protected his men and the armored units of Lt. Col. George S. Patton Jr. that Battery D was supporting.
Seems like the behavior should've been expected from the guy who managed to wrangle Battery D into a unit that would stand and fight.