From June 1940 to September 1943, when Italy was part of the Axis, Ancona was never bombed, being outside the range of both British bombers based in the United Kingdom and American bombers based in North Africa. On 15 September 1943, after the Armistice of Cassibile, German troops occupied Ancona during Operation Achse; at the same time, the Allied advance into southern Italy resulted in the city being now within the range of the Allied air forces.