Wednesday July 20, 1921. Attacking the Ostfriesland.

The Army Air Corps sank the Ostfriesland, the largest German vessel to be subject to the Air Corp's aerial bombing experiment.

It was also the last vessel to be sunk.

The SMS Ostfriesland was a 1908 vintage German battleship and its use as demonstration proved to be a bit more accurate than had been planned for.  The effort was watched by the Secretaries of War and the Navy and Gen. John J. Pershing and only 13 of the 52 bombs launched from Army Air Corps airplanes struck her, a not atypical ratio.  This was, of course, before dive bombing and torpedo runs became the areal norm for attacking surface vessels.

Worse yet, only four of the bombs detonated.

A second run, using two 2,000 lbs bombs, occurred the following day, which did finally sink the former German dreadnought.

While the experiment confirmed what had already been proven, that aircraft could sink any surface ship, it also showed that some ships weren't easy to sink and that conventional bombing, such as engaged in by the Air Corps, had its limitations  In the following years before World War Two the Navy would take this to heart and develop specialized aircraft and weapons for attacking both surface ships and submarines.  The Air Corps, however, continued to take the view that bombers were effective against surface ships, which would prove to be in error in World War Two.

Parliament approved Prime Minister David Lloyd George's peace proposal to the Irish Republicans. The authorization envisioned an offer which granted Ireland complete domestic government, Dominion status, but which reserved defense and foreign relations to the United Kingdom.

If this seems rather limited, it was actually the status that other British Dominions, such as Canada and Australia, had at the time.  It was not until the Statute of Wesminster of 1931 that the Dominions obtained control of their own foreign relations, including the ability to declare war.