After two years of unsuccessful zeppelin, raids, the Germans launched the second phase of their attempt to panic the English on July 7, 1917. Twenty-two Gotha G IV heavy bombers dropped 72 bombs in the first of 52 aerial raids. Although tactically unproductive, the bombings had a deep psychological effect that many Britons would remember when, in 1939, they again searched the skies for planes bearing the black cross