Battle of the Danzig Bay The Battle of the Danzig Bay ( ) took place on September 1 , 1939 , at the beginning of the invasion of Poland , when Polish Navy vessel s were attacked by German Luftwaffe aircraft in Gdańsk Bay ( then Danzig Bay ) . It was one of the first incidents in which naval units had to defend themselves against air attack . History . Eve of the battle . The Polish Navy of the Second Polish Republic ( 1919 – 39 ) was prepared mostly as means of supporting naval communications with France in case of a war with the Soviet Union . However , after it became apparent that the aggressive side would be Germany , and the entrance to the Baltic Sea would be blocked , three out of four Polish modern destroyer s were withdrawn from the Baltic Sea to Great Britain in what was called Operation Peking . The remaining forces , consisting of one large minelayer , one destroyer , five submarines and smaller vessels were to execute two major naval operations , both aimed at disrupting the German naval movement in the area of the Danzig Bay and transit movement between Germany and East Prussia . All submarines were dispatched for their operational zones in the southern Baltic to take part in Operation Worek , an attempt to sink as many German ships as possible . Battle . All the remaining surface vessels were to be dispatched from the naval base in Gdynia to Hel Peninsula , from where they were to start the so - called Operation Rurka . The plan was to lay a naval mine barrier between Hel Peninsula and Danzig to prevent any enemy ship from entering the area . At dusk ten Polish warships left Gdynia for Hel , located on the other side of the bay . There , the ships were to start the minelaying operation . Among them were the destroyer ORP " Wicher " , large minelayer " Gryf " , minelaying minesweepers " Jaskółka " , " Czapla " , " Żuraw " , " Czajka " , " Rybitwa " and " Mewa " and gunboat s " Komendant Piłsudski " and " Generał Haller " . While traversing the Danzig Bay , the flotilla was attacked by a group of 33 German warplanes , mostly Junkers Ju 87B Stuka dive bomber s . The air raid was mostly unsuccessful and the Polish vessels suffered only minor losses . The backbone of the Polish flotilla , ORP " Gryf " with over 300 naval mines on board , remained unharmed . However , soon after the first air raid was repelled , the German bombers returned , around 6 pm . There were no direct hits , but the Polish ships suffered minor damage from close misses and machine gun fire , mainly minelayer ORP " Gryf " and minesweeper ORP " Mewa " . The commanding officer of ORP " Gryf " , Cmdr . Stefan Kwiatkowski was killed by German machine gun fire , and her rudder was jammed . Her executive officer , Lt . Cmdr . Wiktor Łomidze feared that her cargo of mines ( comprising over 33 tonnes of high explosives ) was a danger to the ship and if it was hit by a bomb , it would explode immediately . Because of that , he ordered all the mines to be disposed of in the sea . After the battle . After successful defence against several consecutive air raids , the Polish flotilla arrived at Hel . However , since ORP " Gryf " had abandoned all of its mines and was damaged , the Operation Rurka had to be called off . The only destroyer , ORP " Wicher " , did not receive the orders calling off the operation and went straight to the pre - designed zone of operations to cover the mine - layers . At night , " Wicher " , commanded by Lt . Cdr . Stefan de Walden , spotted two German destroyers , and later a ship misidentified as a light cruiser , but did not attack , not wanting to uncover the operation . After return to Hel Peninsula , both major vessels were there deprived of most of equipment and served as anti - aircraft platforms in the Hel naval base .