What caused the Halifax explosion?
The explosion was caused when two ships collided in the narrowest part of Halifax Harbor on the morning of Thursday, December 6, 1917. The Mont Blanc, a French ship was arriving from New York City filled with munitions for the war in Europe. In addition to the 2925 tons of explosives in its hold, it carried barrels of highly flammable benzol and picric acid on the deck. Unable to travel with its scheduled convoy across the Atlantic, the Mont Blanc went first to Halifax so it could travel with a new convoy. It arrived the night before and had to wait outside the submarine net that protected the harbor. At dawn, it began to more into the harbor. Normally a munitions ship would fly a red flag to warn others of the dangerous cargo, but the Mont Blanc did not raise its warning flag.
