From Lamont, Michigan, Benjamin enlisted in the 5th Cavalry, Company B as a Corporal on August 14, 1862 at Tallmadge, for 3 years service at the age of 34. He took the muster oath on August 27, 1862, and served the remainder of the war with the regiment. He was mustered out at Fort Leavenworth, Kansas, on June 20, 1865. He is buried in the Preston City Cemetery, Franklin County, Idaho.