The Orzeł incident occurred at the beginning of World War II in September 1939, when the interned Polish submarine escaped from Tallinn, in neutral Estonia, to the United Kingdom. Joseph Stalin's Soviet Union used the incident as one of the pretexts to justify its eventual military invasion and occupation of Estonia in June 1940. Orzeł was docked at Oksywie when Nazi Germany attacked Poland and began World War II. The submarine at first took part in Operation Worek but withdrew from the Polish coast on 4 September as the situation evolved. Damaged by German minesweepers and leaking oil, it headed for Tallinn, which it reached on 14 September 1939 at about 01:30. Lieutenant-Commander Henryk Kłoczkowski, the commanding officer, was taken to a hospital the next day for treatment of an unidentified illness from which he had been suffering since 8 September. The Hague Convention of 1907 enjoined signatories, including Germany, from interfering with the right of enemy warships to use neutral ports within certain limits. Initially, Estonia was quite accommodating of Orzeł and helped with the repair of a damaged compressor. However, probably because of German pressure, Estonian military authorities soon boarded the ship, declared the crew interned, confiscated all the navigation aids and maps and started to dismantle the armaments. An Estonian officer removed the naval ensign from the submarine's stern. The crew of ORP Orzeł conspired to escape under the new command of its chief officer, Lieutenant Jan Grudziński, and its new first officer, Lieutenant Andzej Piasecki. That started with Grudziński's sabotage of the torpedo hoist on 16 September, which prevented the Estonians from removing the six aft torpedoes. Since it was a Sunday, another could not be immediately acquired. Meanwhile, Boatswain Władysław Narkiewicz took a small boat around the harbour. Under the guise of fishing, he covertly measured the depth of the planned escape route. Another sailor sabotaged the submarine's mooring lines.