[1][2] At the outbreak of the Civil War, Brady enlisted as a private in the 12th Pennsylvania Infantry.

On July 8, 1861, he accepted a commission as a first lieutenant in the Regular Army's 14th Infantry Regiment.

[4] Immediately after the conclusion of the war, the 14th Infantry was sent to the west coast, where Brady was posted at Camp McDowell, Arizona, accompanied by his wife Henrietta Margaret and their baby daughter.

In September 1866, he was transferred to the 23rd Infantry and was posted to Camp Three Forks Owyhee, Idaho, where he took part in the Snake War.

[5] He was promoted to major in the 18th Infantry in March 1886, and was stationed in Denver until May 1889 when he took command of Fort Hays.