On December 6, 1917, two ships collided in Halifax Harbor in Nova Scotia, Canada. One ship was loaded top to bottom with munitions and the other held relief supplies, both intended for war-torn Europe. The resulting blast flattened two towns, Halifax and Dartmouth, and killed nearly 2,000 people. As if that wasn't devastating enough, a blizzard hit the next day, dumping more than a foot of snow on the area and paralyzing much-needed relief efforts.