The Allies bombed neutral Switzerland 70 time during World War II including the major cities of Zurich and Basel on March 4, 1945. The official explanation is navigation errors on the way to bomb German cities. Some, however, think it was an attempt to pressure the Swiss into ending its economic cooperation with the Nazis. The Swiss, in their turn, shot down or forced to land numerous allied bombers ultimately interning 1,700 American airmen.