Germany claims sinking fourth Polish submarine according to a report of the American Naval Attaché at Berlin, Germany Nr. R562 dated 15 September 1939

Diary note dated Friday 8 September 1939. An item referred to German naval news received that afternoon claiming the sinking of a fourth Polish submarine.(1)

Note

1. With the outbreak of the Second World War the Polish navy possessed four submarine namely the Dutch built Orzel and Sep belonging to the Orzel-class and the French built Wilk, Rys and Zbik belonging to the Wilk-class. The Orzel and Wilk escaped to England, the Sep was damaged on 2 September by the German destroyer Friedrich Ihn, but survived torpedo attacks by German submarines U-18 and U-14 on 3 September although the Germans claimed she was sunk, she escaped to Sweden and was there interned and returned to Polish control in September 1945. The Zbik and Ryw ere also interned at Sweden during the war and returning to Poland in 1945. In the month September were none Polish submarines destroyed as the Germans claimed. 

Source

National Archives. FDR Presidential Library&Museum Roosevelt PSFC000175. War diary Naval Attaché Berlin, volume 1 (1 September 1939-26 May 1940)