A British pilot flew over the Lille Aerodrome and dropped what appeared to be a huge bomb. The German soldiers down below immediately scattered in all directions, but no explosion followed. After some time, the soldiers crept back and gingerly approached the bomb. They discovered that it was actually a large football with a note tied to it that read, April Fool - Gott Strafe England!
Note: 'Gott strafe England' was a slogan used by the German Army during World War I meaning, "May God punish England." Its use by the British aviator was evidently meant to be ironic.