On 31 May, "Sickle" left Malta harbour for a patrol in the Aegean Sea; this was to be "Sickle"s last patrol. On 4 June, she engaged enemy ships on the surface at Mytilene; two sailors were wounded, one killed, and another washed overboard and captured. This man later became "Sickle"s only survivor. She was ordered on 5 June to patrol the eastern approach to the Doro channel. On 6 June, the submarine torpedoed and sank the German merchant ship "Reaumur", and on 7 June a German lighter reported having been missed by torpedoes potentially launched by "Sickle". On 8 June, a submarine that was possibly "Sickle" sank three caïques near Skopelos, and she missed the German transport "Lola" with torpedoes on 9 June. A submarine, again possibly "Sickle", sank the caïque "Efitichia" with gunfire and bombarded a shipyard at Mytilene on 14 June 1944. The submarine was never seen again, and it is considered likely that she was sunk by mines on her way back to Malta in the Kythira Strait on or around 18 June.