Ablockship is aship deliberately sunk to prevent ariver,channel, orcanal from being used as awaterway. It may either be sunk by a navy defending the waterway to prevent the ingress of attacking enemy forces, as in the case ofHMS Hood atPortland Harbour in 1914; or it may be brought by enemy raiders and used to prevent the waterway from being used by the defending forces, as in the case of the three oldcruisersHMS Thetis,Iphigenia andIntrepidscuttled during theZeebrugge raid in 1918 to prevent the port from being used by theGerman navy.
An early use was in 1667, during the DutchRaid on the Medway and their attempts to do likewise in the Thames during theSecond Anglo-Dutch War, when a number of warships and merchant ships commandeered by theRoyal Navy were sunk in those rivers to attempt to stop the attacking forces.
An even earlier use are the six 11th centurySkuldelev ships inRoskilde Fjord, sunk to protectRoskilde from northernVikings. They are now on display in theViking Ship Museum.[1][2][3]
The above is the principal and enduring meaning of 'block ship', but in the mid-19th century the term blockships was applied to two groups of mobile sea batteries developed by the Royal Commission on Coast Defence. The first batch of four was obtained from around 1845 by converting old sailing 74-gun two-deckers, all of themVengeur-classships of the line, into floatingbatteries, equipped with a steam/screw propulsion system. Also called "steam guardships",[4] these conversions involved cutting down to a single deck, withballast removed, and ajury rig installed with a medium 450-horsepower (340 kW) engine for speeds of 5.8–8.9knots (10.7–16.5 km/h; 6.7–10.2 mph). These ships, converted in 1846, wereBlenheim,Ajax,Hogue andEdinburgh. Although these ships were intended for coast defence some of them were used offensively, notably in theBaltic Campaign of 1854 and 1855, where they were an integral part of the British fleet. A second batch of five were similarly obtained from around 1855 by converting other elderly 74-gun ships; these wereRussell,Cornwallis,Hawke,Pembroke andHastings.
The most recent known use of blockships in warfare was during theannexation of Crimea by the Russian Federation. On 6 March 2014, theRussian Navy towed and scuttled the decommissioned cruiserOchakov at the entrance toDonuzlav Bay in westernCrimea, to prevent remaining Ukrainian navy vessels from leaving port.[5] Less than 24 hours later, on 7 March, another blockship, the formerBlack Sea Fleet rescue/diving support vesselBM-416 was scuttled nearOchakov.
Media related toBlock ships at Wikimedia Commons