Bradley Martin Thompson was born on April 16, 1834, in Michigan to Robert Thompson and Maria Short. His father was a farmer who owned $2,500 of real estate by 1850. He grew up and attended school in Milford, Michigan, before enrolling at the University of Michigan. He graduated in 1858. He married Marion Lind around 1860, and they had at least three children: Isidore, born around 1862; Guy, born around 1866; and Ethelind, born around 1875.
In November 1862, he received a commission as a 1st lieutenant in Company C of the 7th Michigan Cavalry. The regiment took part in the Battle of Gettysburg. He eventually received a promotion to captain, and in July 1864, he became a major in the Paymaster’s Department.
He settled in East Saginaw, Michigan, after the war, and he earned a living as a lawyer. By 1870, he and his wife owned $14,000 of real estate and $4,800 of personal property. In 1888, he became a professor in the University of Michigan’s Law School. One writer described him as a “whole souled, generous man…with a genial, gentle and trusting disposition.” He applied for a federal pension in April 1904 and eventually received one. His wife died in 1915, and he died of angina pectoris in Ann Arbor, Michigan, on September 29, 1917.