Almost four million soldiers took part in the Civil War, two million for the Union (50% of combat-aged men) and less than one million for the Confederacy (about 75% of combat aged men). Some were officers, most were enlisted men. Some soldiers brought their families with them, setting up their wives and children in the camps as they went through training. Others struggled to keep in touch with their families by mail.
Life in the military was dull and uncomfortable for most soldiers on both sides. Food was usually disgusting, and sometimes inedible. Soldiers drilled and drilled until they were sick of it. When they were not engaged in battle, soldiers would keep themselves occupied in camp. Some were placed on picket duty, charged with the responsibility of keeping watch for enemy troops or threatening attacks.
Civilian merchants, called sutlers, accompanied the army. They sold items that relieved the tedium of camp life. While the variety was welcomed by many, sutlers usually charged exorbitant prices for their wares. These items included stationary, baked goods and liquor.
Nurses sometimes visited or traveled with troops, helping tend to the sick and wounded. In addition to the medical care they provide, many of these women brought a touch of home to the discouraged and disillusioned soldiers, softening the effects of the cruelty of the fighting. Chaplains from different faiths also provided spiritual comfort, especially for the dying.
Troops often sang songs and played makeshift instruments to lift their spirits and pass the time. Sentimental songs such as "Home, Sweet Home" and "Annie Laurie" were popular among soldiers on both sides, while Union soldiers added patriotic songs like "John Brown's Body" (which shares the tune of "Battle Hymn of the Republic"), "Yankee Doodle" and "The Battle-Cry of Freedom." Most regiments and brigades had bands, which sometimes played concerts of popular and classical music for the troops and the local residents. There were instances of concerts across the lines, as Union musicians played patriotic songs like "Yankee Doodle," which the Confederate musicians answered with "Dixie." Such concerts usually ended with a shared tune, such as "Home, Sweet Home."

Soldiers on both sides gambled. Some played baseball, which was a new game in the 1860s. Others turned to heavy drinking and other unsavory activities to escape from the horrors of battle and the discomfort of the camp. This became a problem when drunken soldiers and officers could not maintain order in the camp or conduct themselves in battle.