On 29 April, "Oxley" and "Otway" (which had also been recommissioned into the RN) left Sydney for Malta. During 1939, the submarine was based at Portsmouth as part of the 5th Submarine Flotilla. At the onset of war the submarine was a member of the 2nd Submarine Flotilla. From 26 to 29 August 1939, the 2nd Submarine Flotilla deployed to its war bases at Dundee and Blyth. Following the outbreak of the Second World War, "Oxley" was assigned to patrol duties off the coast of Norway. She was assigned the pennant number 55.