Italian and German military engineers began working on clearing the canal on 2 May. The first Italian supply convoy managed to pass through the canal on 16 May, arriving at Pireaus. The late arrival of fuel carried by the Italian convoys caused the airborne invasion of Crete to be postponed by two days to 20 May. The Germans prevailed after seven days of fighting, forcing an Allied withdrawal to Egypt. With the conclusion of Operation Marita, Greece was subjected to a Triple Occupation by Germany, Italy and Bulgaria.