On the morning of September 25, 1911, the French battleship Liberté lay quietly at anchor in Toulon harbor. The fleet was already grieving the loss of sailors from a smaller accident aboard the cruiser Gloire, and preparations for their funeral were underway. At first light, there was no reason to expect anything but another routine day. Then smoke began to curl from Liberté’s forward turret, followed by small blasts that sent rescue boats rushing to her side. Eighteen minutes later, a cataclysmic explosion ripped the battleship apart and shook the city. More than two hundred men were dead, hundreds more injured, and the harbor was littered with wreckage and bodies. The cause was not sabotage or enemy action but something far more damning: a fatal flaw in the very powder that armed the French fleet. This was France’s deadliest peacetime naval disaster, and its story is unforgettable.