In the ocean of air, however:
The Wiki indicates:
War in the AirBombers based in England make a 1,500 mile round trip to attack Spezia, ItalyThe USAAF carries out ten raids over KiskaHow to cite this article: Rickard, J (28 December 2007), 13 April 1943, http://www.historyofwar.org/secondworldwar/date/1943_04_13.html
And the Chronology of World War II advises:13: Radio Berlin announces the discovery by Wehrmacht of mass graves of Poles purportedly killed by Soviets in the Katyn massacre.
- Beginning of Warsaw ghetto uprising. [766.40]
- (evening) 211 British bombers attack La Spezia, Italy, especially the naval base with three battleships in port. Four Lancaster bombers are shot down. The battleships are unharmed. [84.165]