From August 11-September 14, 1779 Samuel Mason while at Fort Henry accompanied Colonel Daniel Brodhead and his 8th Pennsylvania Regiment of the Continental Army combined with militia troops from Fort Pitt to destroy ten tribal villages of the pro-British Seneca tribe in northeastern Pennsylvania during the Sullivan Expedition in retaliation for the devastating Iroquois attacks in the Cobleskill, Wyoming Valley and Cherry Valley massacres of 1778.