70 years ago on April 1 the United States air force accidentally bombed the Swiss city of Schaffhausen, mistaking it for a German target. Some 400 incendiary and demolition bombs were dropped, killing 40 people and destroying large parts of the city. (SRF/swissinfo.ch)
About 15 B24 planes unleashed their bombs, mistaking the city for the target of Ludwigshafen am Rhein near Mannheim, about 235 km north of Schaffhausen. Bad weather had broken up the American formation over France and winds that nearly doubled the groundspeed of the bombers confused the navigators. The radar systems also failed to function. As Schaffhausen is on the north side of the River Rhine, it was apparently assumed to be the German city.
Switzerland was neutral during the Second World War but the fear of being bombed was acute. Up until then, air raid warnings had been sounded many times in Schaffhausen with no follow up attacks, so people felt relatively safe. When the alarm went off on April 1, many did not take it seriously and failed to take cover.
US President Franklin Roosevelt sent a personal letter of apology to the mayor of Schaffhausen and by October 1944, $4 million had been paid in restitution. After the bombing, the Swiss began to paint their roofs with the white cross of the Swiss flag.