Outside of his artistic career, Brooke was known as a devout Christian who led mission meetings on Sundays at the Fauquier County Courthouse. He kept active in Warrenton affairs for much of his adult life; in 1882 he painted a flag to be presented to the Warrenton Rifles upon their journey to Yorktown to participate in the centennial celebration of the battle there, and on November 15, 1889, he was among those who saved William Washington's portrait of John Marshall from being destroyed in a fire that engulfed the courthouse.