Defense of the Coast of Poland in the September Campaign
1939 CE.
Shown on the map at 54.633°, 18.783°.
The Battle of Danzig Bay (Polish: bitwa w Zatoce Gdańskiej) took place on 1 September 1939, at the beginning of the invasion of Poland, when Polish Navy warships were attacked by German Luftwaffe aircraft in Gdańsk Bay (then Danzig Bay). It was the first naval-air battle of World War II.
Text from the Wikipedia article Battle of Danzig Bay, licensed CC BY-SA 4.0.