The Confederate battle cry known as the rebel yell sounded nothing like a cowboy’s yee-haw. Soldiers and correspondents described a noise that began low in the diaphragm and climbed through rhythmic crescendos into a high, piercing shriek, comparing it to a dying rabbit, a cougar, or a wolf’s howl. Regiments practiced it, and one Virginia cavalry battalion became so known for its coordinated cry that it was nicknamed the Comanches.

The only audio comes from elderly veterans filmed at reunions, including the 75th anniversary of Gettysburg in 1938, and a North Carolina infantryman and a Virginia cavalryman produced nearly identical yells. The episode examines theories that the cry blended Scots-Irish Highland charges, Comanche war whoops, Moorish-influenced ululation, and fox hunters’ calls, and that it was heard in Bleeding Kansas before 1861. It also looks at why officers ordered men to holler during charges, and how the name later landed on a bourbon and a Billy Idol song.

• One early written account spelled the yell as a low whoa followed by a long, vibrating hooey.
• A veteran asked to demonstrate it at a society dinner refused, saying it could not be done standing still with false teeth.
• A writer who fought at Chickamauga called it the ugliest sound any mortal ever heard.
• One general ordered his men to yell because they had run out of ammunition.
• A former Confederate surgeon would leap up and give the yell at the opera when the orchestra played Dixie.