At 01.55 hours on 27 Jun, 1941, U-564 (Suhren) fired three single torpedoes in one minute intervals at the convoy HX-133 about 300 miles south of Iceland and observed three hits. The Maasdam and Malaya II were sunk and the Kongsgaard was damaged.

The Maasdam (Master J.P. Boshoff) was hit by one torpedo on the port side at #2 hold. Several lifeboats were destroyed, but the most of the 48 crew members and 32 passengers (17 American Red Cross nurses and US Marines under Maj Walter L. Jordan, the advance detail for the Marine Detachment at the American Embassy in London) safely abandoned ship before she sank. Two passengers were lost. 44 survivors, among them nine of 17 American Red Cross nurses, were rescued by the Norwegian motor tanker Havprins and landed at Barry. The remaining survivors were picked up by another Norwegian vessel.