Bliss wrote this song after hearing Daniel Whittle relate the following incident from the American civil war:
Just before [William Tecumseh] Sherman began his famous march to the sea in 1864, and while his army lay camped in the neighborhood of Atlanta [Georgia] on the 5th of October, the army of Hood, in a carefully prepared movement, passed the right flank of Sherman’s army, gained his rear, and commenced the destruction of the railroad leading north, burning blockhouses and capturing the small garrisons along the line.
Sherman’s army was put in rapid motion pursuing Hood, to save the supplies and larger posts, the principal one of which was located at Altoona Pass. General Corse, of Illinois, was stationed there with about fifteen hundred men, Colonel Tourtelotte being second in command.
A million and a half rations were stored here, and it was highly important that the earthworks commanding the pass and protecting the supplies be held. Six thousand men under command of General French were detailed by Hood to take the position.
The works were completely surrounded and summoned to surrender. Corse refused and a sharp fight commenced. The defenders were slowly driven into a small fort on the crest of the hill. Many had fallen, and the result seemed to render a prolongation of the fight hopeless.
At this moment an officer caught sight of a white signal flag far away across the valley, twenty miles distant, upon the top of Kenesaw Mountain. The signal was answered, and soon the message was waved across from mountain to mountain:
Hold the fort; I am coming. W. T. Sherman.
Cheers went up; every man was nerved to a full appreciation of the position; and under a murderous fire, which killed or wounded more than half the men in the fort—Corse himself being shot three times through the head, and Tourtelotte taking command, though himself badly wounded—they held the fort for three hours until the advance guard of Sherman’s army came up. French was obliged to retreat.