Friday (13th) Nothing Afloat

Nothing appears to have happened in re: the U.S. Navy on TUES 13 APR 1943.

In the ocean of air, however:

War in the Air

Bombers based in England make a 1,500 mile round trip to attack Spezia, Italy

The USAAF carries out ten raids over Kiska

How to cite this article: Rickard, J (28 December 2007), 13 April 1943, http://www.historyofwar.org/secondworldwar/date/1943_04_13.html

The Wiki indicates:

13: Radio Berlin announces the discovery by Wehrmacht of mass graves of Poles purportedly killed by Soviets in the Katyn massacre.

And the Chronology of World War II advises:

April 13

• 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]