According to John D. Billings, author of Hardtack & Coffee, one of the typical daily bugle calls was a Watering Call. Upon hearing this call, artillery drivers and all cavalry rank and file went to the picket rope to water their horses.
This was a simple task when the army camped near a river, which was often the case. When it wasn’t, thirsty horses were ridden a mile or two—sometimes longer—to find a pond or stream.
Finding a sufficient amount of water for thousands of animals was no small task.
General McClellan had about 38,800 horses and mules after the Battle of Antietam in September of 1862. 56,499 horses and mules were in the army’s care when they crossed the Rapidan River in 1864.
All animals weren’t taken to the same stream for watering because troops spread out for miles.
A drought in the summer of 1864 brought serious problems. No rain fell for several weeks. Soldiers were hard-pressed to find enough water for themselves. They’d find an old stream where only mud remained. Scooping out holes in the mud, soldiers patiently waited for “warm, milky-colored fluid to ooze from the clay.” The water came a drop at a time until it filled a dipper for the thirsty soldier.
Hundreds of men carried empty canteens through forests and valleys in search of water.
When the drought continued, Union soldiers dug wells. To their relief, they found an abundance of water 10-12 feet below ground. These wells met the needs of soldiers and their animals.
-Sandra Merville Hart
Billings, John D. Hardtack & Coffee, University of Nebraska Press, 1993.
Villanueva, Jari. “Twenty Bugles Calls,” The United States Air Force Band, 2017/03/14 http://www.usafband.af.mil/shared/media/document/AFD-150220-028.pdf.