The German Panzerschiff (Pocket Battleship) "Deutschland ,Tanker "Neptun" and the torpedo boat "Leopard" were lying at anchor outside the harbour of Ibiza (Ibiza and Palma, known as the Balearic islands ,were loyal to General Franco's forces) on the 29/05/1937 , which was during the Spanish Civil war, when they were attacked by two Republican SB2- Katiuskas planes piloted by Soviet pilots ( the Soviets backed the Republican forces and sent military supplies and personnel during the Spanish Civil war ).
Apparently they mistook the "Deutschland for Franco's flagship "Canaris".
As a result of this attack the Germans lost 35 sailors and 75 were wounded.
The injured and wounded were taken to Gibralter where the British saw to the wounded and the dead were buried, only to be exhumed 10 days later at Hitlers order to be reburied at the Naval Cemetery in Wilhelmshaven . There a stone memorial was erected ,which still exists today.
In retaliation Hitler ordered the Republican Spanish coastal town "Almeira" .in Andulusia , to be bombed on 31/05/1937 by the Panzerschiff " Admiral Scheer" accompanied by the torpedo boats " Leopard, Luchs,Albatros and Seeadler"
Go to link to see photo of memorial:
www.dropbox.com/s/ssay5vvk2xnnezj/370.jpg?dl=0