Day 199 March 17, 1940

British Admiralty admits the vulnerability of the Home Fleet in Scapa Flow to air attack, after yesterday’s air raid, and orders the fleet to sea during the next moonlight period on March 19 to 26. Predicting this move, German submarines U-57, U-19, U-21 and U-22 begin moving into position to attack British ships leaving Scapa Flow.

At 11.25 PM, U-38 sinks Danish MV Argentina (carrying general cargo from Copenhagen to South America, via Las palmas, Spain) with one torpedo east of Shetland Islands, Scotland, en route to South America. All 33 hands on board are lost.
http://www.uboat.net/allies/merchants/ships/294.html