The law of accumulating catastrophe. Often applied to nautical situations. Often a disaster beginning with one simple error that causes a domino effect.
Bill was sailing along when a shackle parted on the jib stay. The mast fell over the side. When Bill tried to engage the engine, the prop picked up some of the rigging and stalled. The wind and current pushed his boat until it ran aground on the beach. He had become an unwitting victim of Beare's law of accumulating catastrophe.