In 1774, Brenton was commissioned a Captain by Colonel Angus McDonald, who mustered roughly 400 men to take part in the Wakatomica Campaign of Dunmore's War.
The Shawnee settlements of Wakatomika (present day Dresden, Muskingum County, Ohio) as well as four other villages were burned.
They spent the winter in Harrodsburg, and in spring of 1780 settled on the south bank of Clarks Creek at the ford northeast of Danville (now Boyle County, Kentucky).
[1] In 1782, Brenton was commissioned a Major and made fifth in command of the Crawford Expedition,[2][3] intended to put an end to Indian attacks on frontier settlers.
His coolness and bravery in the face of imminent danger were long after alluded to by his surviving comrades, in terms of the highest commendation.