He was a member of the Wisconsin State Assembly, representing the western half of Vernon County during the 1870 and 1872 sessions.

Earlier in life, he served as a colonel in the Union Army during the American Civil War.

Reuben May was born in Robinson Creek, in Pike County, Kentucky, the son of a wealthy and well-established family.

He grew up on his father's estate, and served as an officer in the Kentucky Militia, rising to the rank of lieutenant colonel during the Mexican–American War.

They organized a regiment on Barnes' estate, bringing in willing men and collecting rifles from known Confederate sympathizers in the surrounding communities.

[4] When they had enough armed men, their unit mustered into federal service as the 8th Kentucky Infantry Regiment in the Fall of 1861.

[3] In the early months in federal service, the regiment was stationed in Union strongholds in central Tennessee.

During these months, May worked to educate the officers of the regiment in principles and tactics, and generally served as drillmaster for the enlisted men.

[4] May distinguished himself at the Battle of Perryville, leading a small detachment which captured a number of Confederate prisoners.

[6] After the battle, the regiment was camped at Murfreesboro for the next several months and May recuperated from his injuries at Nashville until April.

[3] While the war had raged in Tennessee and Kentucky, the homes of many Union loyalists had been raided and May's wife and children had fled the state to Wisconsin in 1863.

[7] With May's blessing, they purchased a large farm in the town of Jefferson, Vernon County, Wisconsin.

[3] Politically, May had been a Democrat before the war, and voted for John Bell in the 1860 United States presidential election.