On May 24, 1832 Mack enlisted in Captain John S.C. Hogan's company of militia with the rank of 1st Sergeant. Mack's company was too small to be an effectual military organization, and the only noteworthy event was when the company discovered the aftermath of the Indian Creek Massacre (which occurred May 20) at the Davis home some twelve miles north of Ottawa where fifteen whites were slain. By about the second week of June, army regulars from Michigan began arriving in Illinois to continue the war, and by mid-June Mack's company of militia was dissolved.