The US Air Force accidentally bombed the Swiss city of Schaffhausen.
Schaffhausen lies on a small strip of land which is almost completely nestled within Germany’s borders, so when the US bombers’ navigation went slightly awry, they thought they were bombing Germany. 40 Swiss Civilians lost their lives that day. President Franklin D. Roosevelt personally wrote a letter of apology to the mayor of Schaffhausen, along with a gift of four million US dollars.