November 21, 1914, three Avro 504s left Belfort, France, for Friedrichshafen, Germany. The object of these Allied visitors: destroy the hated enemy Zeppelins moored in giant woodsheds.

Because Belfort was crawling with German spies, the British planes and pilots hand-picked for the mission were brought in secretly and hidden until the raid began. E.F. Briggs, J.T. Babington, and S.V. Sippe took off. Arriving at Lake Constance, they flew a mere 10 feet above the water. At Friedrichshafen, the pilots climbed, dove, and dropped their 20-pound bombs on target, crossing back and forth so fast that the panicked soldiers and civilians on the ground thought there were six of them.

The three uninvited guests did extensive harm. Their bombs fell within an area of 700 square yards in and around the Zeppelin sheds and gas works. One Zeppelin was almost completely destroyed; others were seriously damaged. The gas works lost thousands of cubic feet of precious hydrogen in an explosion that sent flames hundreds of feet in the sky.

As a result of this raid, the Germans went to great pains to guard Friedrichshafen from further attacks. But it was never attacked again. All their precautions were in vain. After all, a surprise party isn’t a surprise if people know you’re coming.