[44] According to Harrison's report, the losses from his brigade were "very slight" compared with those of Confederate forces; he thought this was because of battlefield topography, writing: "I believe, that the enemy, having the higher ground, fired too high."[45] Harrison later supported the creation of an Atlanta National Military Park which would have included "substantial portions" of the Peachtree battlefield, writing in 1900: “The military incidents connected with the investment and ultimate capture of Atlanta are certainly worthy of commemoration and I should be glad to see the project succeed.”[46]

Surrender of Atlanta and promotion
After the conclusion of the Atlanta Campaign on September 2, 1864, Harrison was among the initial Union forces to enter the surrendered city of Atlanta; General Sherman opined that Harrison served with "foresight, discipline and a fighting spirit".[47] Following the Atlanta Campaign, Harrison reported to Governor Morton in Indiana for special duty, and while there he campaigned for the position of Indiana’s Supreme Court Reporter and for President Lincoln's reelection; after the election he left for Georgia to join Sherman's March to the Sea, but instead was "given command of the 1st Brigade at Nashville.