Largest manmade explosion before nuclear weapons

On 6 December 1917 during the First World War, a Norwegian ship, the SS Imo, and a French ship, the SS Mont-Blanc, which was carrying a 2,653 tonnes (5,848,864 lb) cargo of picric acid, TNT, gun cotton and benzol bound for Europe, collided while the latter was leaving Halifax harbour to join a convoy off the coast of Nova Scotia, Canada. The collision set off the largest manmade explosion before the advent of nuclear weapons, taking into account deaths, explosive force and radius of destruction. The resulting explosion, rated at 2.9 kilotons of TNT killled - according to an estimate compiled by the Halifax Foundation in 2002 – 1,951 identified people and injured another 9,000. The destruction covered 325 acres, almost wiping out a complete district in the nearby town of Halifax, and the incident was subsequently named the “Halifax Explosion”.