 After completing the clandestine reconnaissance mission , U @-@ 38 returned to raiding duties and sank three ships , two British and one Greek . The British steam freighter SS Thomas Walton was sunk on 7 December . The Greek steam freighter SS Garoufalia was destroyed on 11 December , as was the British steam freighter Deptford on 13 December . After an operational period of four and a half weeks , U @-@ 38 returned to Wilhelmshaven on 16 December . 
