Willis A. Babcock's American Civil War diary begins near Washington, D.C., where his company had been since June 1863. While at Fort Carroll, his entries largely contain descriptions of his duties in camp (drills and guard, police, or orderly duties), as well as rare sight-seeing trips in the city. He occasionally mentions his meals, recording one day in March where he had roast turkey for dinner--several of his friends caught seven turkeys the previous day. Like many soldiers, Babcock frequently records the weather in his diary. In May of 1864, the artillery unit moved to Fort Willard, Virginia. For most of that month, Babcock's diary continues to record picket and guard duties, as well as inspections and dress parades. On May 27, the regiment marched to Washington and loaded on to boats headed down the Potomac River. He spent several days on board the U.S. Transport Jefferson before marching from Port Royal to Bowling Green, Virginia.

In early June, the regiment was encamped at General Burnside's Headquarters near Cold Harbor, Virginia. On June 5, 1864, Babcock writes they were being shelled, which resulting in the "killing [of] one man from Co. K....+ one from Co. M. was wounded. this is the first time we have been under fire." He records several days of shelling before moving toward Petersburg. For most of June, July, and into August, Babcock's diary includes lengthy entries of his experiences from the rifle pits in Petersburg, as well as camp life. On July 30, he writes "losses very heavy on both sides our men occupy the same ground they did this morning. a total failure on our side." By mid-August, the 10^th New York Heavy Artillery was camped at Fort Whipple, in Arlington, Virginia.

In early September, Babcock's entries find him increasingly ill and excused from duty. The regiment left for the Shenandaoh Valley in October and on October 8, Babcock writes, "slept in Hospital to night for the first time since I have been a soldier." He was transferred from Alexandria to Lincoln Hospital in Washington, D.C., where he remained until November. His entries for October are very brief. From November 6 to the end of the year, Babcock's diary is about his activities at home while on furlough.