HMS B9

HMS B9 was a Royal Navy B class submarine, built at Vickers, Barrow-in-Furness, launched 24 January 1906 and completed 28 April 1906.

B9 was deployed to the Mediterranean soon after the outbreak of World War I. Due to the lack of spare parts this group of submarines were not used after September 1915. In 1917 the Italian Navy converted B9 into to surface patrol boat S9 to serve in the Adriatic.

On 29 March 1916 B9 was attacked by Austrian aircraft.

B9 was sold on 31 October 1919 in Malta to Messrs. Francotosti.