Thomas Trueman was born in England in about 1625. Trueman arrived in Maryland in 1651, where he involved himself in local politics. He served in Maryland lower house in 1661 and 1662 and served in the upper house from 1666 to at least 1669. A major in the colonial militia, in 1676 Trueman led an expedition against the Susquehannock, besieging them at a fort in an attempt at retribution for the death of a colonist who had been killed by a member of a separate American Indian tribe. When the Susquehannock chiefs exited the fort under a flag of truce, Trueman's troops killed them. The remaining Susquehannock left the area and Trueman was impeached from his position. He died in St. Mary's County, Maryland on December 6, 1685.