"U-48" left her home port of Kiel on 19 August 1939, before World War II began, for a period of 30 days. The submarine travelled north of the British Isles, into the North Atlantic and eventually into the Bay of Biscay. She then proceeded to cruise to the west of the Western Approaches, two days after Britain and France declared war on Germany. It was here that she spotted her first target, the 5,000-ton SS "Royal Sceptre". "U-48" attacked the merchant ship with her deck gun on 5 September 1939. All of the crew took to the lifeboats except the Radio Officer who remained transmitting "SOS". He was taken prisoner by "U-48", but then released to the lifeboats as Schultze praised his courage. He verified that the lifeboats were provisioned with food and water. "U-48" then stopped the SS "Browning". The crew abandoned their vessel, but Schultze told them to return to their ship and pick up the crew of "Royal Sceptre". However "Browning" was en route to Brazil, so it was not immediately realised that they had survived. Winston Churchill, then First Lord of The Admiralty, assumed the worst, that the crew and sixty passengers were lost. He declared the sinking to be "U-48" stopped, searched and released several neutral ships before encountering and sinking "Winkleigh" on 8 September 1939 after her crew had taken to the lifeboats.