21st June 1921
The former German submarine U-117 is sunk by U.S. Navy Felixstow F5L flying boats as a demonstration and target practice.
The Bristol 10-seater, designed for passenger transport, makes its first flight (only three of the planes are built)
Johannes Schober, the Chief of Police of Vienna (and later founding president of Interpol), becomes the new Chancellor of Austria.
Ship Losses:
USS G-1 (United States Navy) The decommissioned G-class submarine was sunk as a target in 100 feet (30 m) of water in the East Passage of Narragansett Bay, 625 yards (572 m) bearing 42 degrees true from Taylor Point, Jamestown, Rhode Island, at 41°30.889′N 071°21.246′W by eight depth charges dropped by the minesweeper
USS Grebe ( United States Navy).
Islandia (United Kingdom) The cargo ship sank at Piraeus, Greece.[141] Ship was refloated on 27 June.