This 45p stamp from 2001 celebrates a centenary of Royal Navy submarines. It shows the HMS Unity submarine from 1939.
Having introduced the U-boat during the First World War, Germany again put submarines to devastating effect in World War 2. During the Battle of the Atlantic, which lasted from the first day to the last day of the war, German U-boats attempted but ultimately failed to cut off Britain's supply routes. The 'Ultra' intelligence, gleaned from the cracked code of the Enigma machines, was vital in turning the tide of the battle at sea. Daring missions to sink U-boats gathered essential papers which allowed Enigma to be deciphered.
HMS Unity was one of the numerous, but small, U class submarines. With its fellows HMS Undine and HMS Ursula, Unity was originally commissioned from Vickers as an unarmed target for anti-submarine vessels. However, since placing the order for the vessels in 1936, policy had changed and the first three Undine class were modified during their construction to carry torpedoes, moving them from target practice to real warfare.
From their first sea trials, the three boats demonstrated excellent manoeuvrability despite their relatively low cost production. Indeed, one of the most successful British submarines of the war was a U class: the HMS Upholder, under the command of Malcolm Wanklyn, VC. HMS Unity itself was lost following a collision with a Norwegian vessel in 1940.
The Submarine stamp issue featured boats from different decades of the Twentieth Century, as well as four flags. The other submarine classes featured were the Holland Class (1901), the Swiftsure Class (1973) and the Vanguard Class (1992). The flags were the White Ensign, worns by all Royal Navy ships and submarines, the Union Jack, the flag of the Chief of the Defence Staff and the Jolly Roger flow by the submarine HMS Proteus. The stamps were designed by D Davis.