Born in Clintonville, New York, Brush was orphaned at age 4 and was raised by his grandfather until he left to enter business college at age 17. During the Civil War he enlisted in the First New York Artillery in 1863, and after the war's end he went into business running clothing stores in Albany, Troy and Lockport, New York. He moved to Indianapolis in 1875, eventually opening a department store, and became involved in local baseball as a means of promoting his store. He built a ballpark in 1882, and it became home to the Indianapolis Hoosiers of the American Association for their only major league season in 1884; they played in the Western League before that circuit folded after the 1885 campaign.