1st Brigade, 3rd Division, XXIII Corps James William Reilly (May 20, 1828 – November 6, 1905) was a lawyer, politician, and soldier from the state of Ohio who served as a general in the Union Army during the American Civil War.

In 1858, he entered politics, and was elected as a Republican to the Ohio House of Representatives, where he eventually supported the policies of President Abraham Lincoln.

After training at Camp Massillon, he and his men were assigned to various garrisons and posts in Kentucky, where they operated against Edmund Kirby Smith and John Hunt Morgan.

Reilly and the regiment moved to Covington, Kentucky, on September 1, 1862, in preparation for the Defense of Cincinnati against a threatened Confederate invasion by troops under Kirby Smith.

In the summer of 1863, Reilly's 104th OVI was assigned to Maj. Gen. Ambrose Burnside's Army of the Ohio during its campaign in East Tennessee, including operations around the Cumberland Gap.