Halifax Harbor Explosion occurs.

The blast kills nearly 2,000 people, injures another 9,000, leaves 25,000 homeless and destroys much of the city. The largest man-made explosion prior to the detonation of the atom bomb over Hiroshima in 1945, it is caused by the Norwegian steamer Imo and the French munitions ship Mont Blanc. When news of the tragedy reaches Boston, Gov. Samuel McCall names Boston businessman Abraham Ratshesky to lead a relief effort. A train is dispatched to Halifax that night carrying medical personnel and supplies, food, clothing, and $750,000 in donations. To show its appreciation, the Province of Nova Scotia and the city of Halifax donate a Christmas tree to Boston in 1918 and annually, beginning in 1971.