Answer: Maritime Accident
Prior to the advent of the atomic bomb, the largest explosions created by man were those created by more traditional explosives like TNT. The more explosive material present, the bigger the explosion and, practically speaking, there were very few times that huge amounts of explosives were in one place let alone in one place and detonated.
On the morning of December 6, 1917, however, ill fate would have both a large volume of explosives and something to ignite them in the same place. In the Narrows, a small strait connecting the upper part of Halifax Harbor to Bedford Basin in Halifax, Nova Scotia, Canada, two ships collided. On any other day, this would have been a very minor issue as the collision was very low speed, but on this particular day, a set of unique circumstances led to a tragic disaster.
The first ship was the SS Mont-Blanc, a French cargo ship heavily laden with high explosives en route to France. At approximately 8:45 a.m., the unladen SS Imo, a Norwegian ship chartered by the Commission for Relief in Belgium to pick up supplies in New York, collided with the SS Mont-Blanc after refusing to yield in the strait. The collision toppled barrels of benzol, a highly flammable liquid, and a spark from the SS Imo grinding along the hull of the SS Mont-Blanc set the liquid ablaze.
The explosion resulting from the detonation of the SS Mont-Blanc’s cargo 19 minutes after the collision was equivalent to 2.9 kilotons of TNT. The shock waves from the explosion destroyed or badly damaged every structure in a 1.6 mile (2.6 kilometer) radius around the blast site, killing approximately 2,000 people and injuring 9,000 more. The explosion was so forceful that part of the SS Mont-Blanc’s anchor landed 2 miles (3.2 kilometers) from the blast site and the remains of the forward gun landed 3.5 miles (5.6 kilometers) away.
The explosion was so powerful, in fact, that it was later used as a frame of reference to describe how powerful early atomic bombs were, with newspapers describing the power of the Little Boy atomic bomb as seven times more powerful than the Halifax Explosion.
Image courtesy of the Library and Archives Canada.