HMS B9

Ordered as part of the 1904–1905 Naval Programme, B9 was built by Vickers at their Barrow-in-Furness shipyard. She was launched on 26 January 1906 and completed on 28 April at a cost of £47,000. The B-class submarines were initially assigned to the Third Division of the Home Fleet, based at Portsmouth and Devonport, and were tasked with coastal-defence duties and defending the Straits of Dover in wartime. In 1912, HMS B9, HMS B10 and HMS B11 were transferred to Malta.^[4]

After the start of the First World War and the unsuccessful pursuit of the German ships Goeben and Breslau in August 1914, the B-class submarines were transferred to the Dardanelles area in mid-September to prevent any breakout attempt by the German ships. After the arrival of the larger and more modern E-class submarines in early 1915, the B-class boats began to return to Malta. After the Kingdom of Italy joined the Allies in May 1915, the B-class submarines in the Mediterranean were transferred to Venice to reinforce Italian forces in the northern Adriatic.^[5] B9, B7 and B8 were the first to arrive in Venice on 11 October and B9 made their first patrol a week later. She saw no targets and returned to Venice three days later. The five British submarines made a total of 13 patrols off the Austro-Hungarian coast before the end of 1915, hampered by bad weather and drifting mines, followed by 13 more in the first two months of 1916.^[6]

While on a patrol off the entrance to Pola on 29 March, B9 was spotted and unsuccessfully attacked by a pair of Lohner L flying boats. After diving the boat had great difficulty maintaining her proper depth of 60 feet (18.3 m) and three times descended below 100 feet (30.5 m) before her batteries were exhausted. The following month, the boat began a refit at Venice that lasted for several months. On 18–20 October, B9 made the last patrol, an uneventful one, by a B-class submarine in the Adriatic off the coast of Istria. Replaced by more modern H-class submarines, the B-class boats returned to Malta on 9 November to be converted into surface patrol boats, armed with a 12-pounder (3 in (76 mm)) gun. Redesignated as S9 in August 1917, the boat was assigned to patrol the Otranto Barrage that was intended to prevent the Austro-Hungarian Navy from breaking out of the Adriatic, although she proved to be very unreliable in service. Paid off at Malta, she was sold for scrap in 1919.^[7]

• Akermann, Paul (2002). Encyclopaedia of British Submarines 1901–1955 (reprint of the 1989 ed.). Penzance, Cornwall: Periscope Publishing. ISBN 1-904381-05-7.
• Gardiner, Robert & Gray, Randal, eds. (1985). Conway's All the World's Fighting Ships 1906–1921. Annapolis, Maryland: Naval Institute Press. ISBN 0-85177-245-5.
• Harrison, A. N. (January 1979). "The Development of HM Submarines From Holland No. 1 (1901) to Porpoise (1930) (BR3043)". United Kingdom Ministry of Defence. Retrieved 16 September 2019 – via RN Subs.
• Kemp, Paul & Jung, Peter (1989). "Five Broken Down B Boats: British Submarine Operations in the Northern Adriatic 1915–1917". Warship International. XXVI (1): 10–29. ISSN 0043-0374.
• Wilson, Michael (1981). "The British 'B' Class Submarine". In Roberts, John (ed.). Warship Volume V. London: Conway Maritime Press. pp. 38–44, 74–79. ISBN 0-85177-244-7.