A high-spirited idealist who craved excitement when he enlisted in the Eighth Illinois Volunteers for three months and reenlisted for three years, Wills, of Canton, Illinois, wrote frequently to his sister Mary Emily Wills and kept a diary of General William T. Sherman's campaigns during the last year of the war.

A student and store clerk before enlisting, Wills found that army life "beats clerking." He enlisted as a private at the age of twenty-one and by twenty-four was a major.

He had thought he might receive an infantry commission eventually, but when the opportunity arose for promotion to first lieutenant in the Seventh Illinois Cavalry, "cupidity and ambition" caused him to abandon the Eighth, enabling him to hold rank "without so much walking." For a while, he seriously rued his lack of action, but his enthusiasm for carnage waned as he marched with Sherman to the sea.

Wills matured in the army. He joined solely to preserve the Union, and his early comments on slaves "lacked sympathy, even decency," according to John Y. Simon. Later he came to the point where he would arm blacks - in part, with an eye toward gaining rank by leading the new regiments. Yet he was not blind to the anomalies of a slave society.

Wills died in 1883. To preserve his memory, his sister (now Mary E. Kellogg) printed his diary in 1904. Two years later, Kellogg combined the diary with the letters Wills had written to her earlier in the war.