John DeCew held the rank of Captain and commanded a company of the 2nd Lincoln Militia. He was captured by American forces in May, 1813 while returning home following the British defeat at the Battle of Fort George and incarcerated in Philadelphia, Pennsylvania. He escaped from his captivity in April, 1814 and returned to Niagara to take part in the remainder of the war, including the Battle of Lundy's Lane. During his incarceration, his house in Thorold township (DeCou House) was used by the British army as a headquarters and stores. It was to here that Laura Secord journeyed to warn the officer in charge, James Fitzgibbon, of the American advance prior to the Battle of Beaver Dams. DeCew would retain his commission in the militia until 1823.