In 1967, Paddy Roy Bates, a former British Army major, occupied HM Fort Roughs, an abandoned Maunsell Sea Fort situated roughly seven miles off the coast of Suffolk, England. Constructed during World War II to guard against German minelayers, the concrete and steel tower stood in international waters at the time of its abandonment. Bates declared the structure the independent Principality of Sealand, claiming sovereignty under the principle of terra nullius.
The legal foundation of Sealand was unexpectedly tested in 1968 when Royal Navy vessels approached the fort and Bates fired warning shots. A British court ruled that because the fort sat outside the UK three-mile territorial waters limit, English courts had no jurisdiction over the incident. When the UK extended its territorial waters to twelve miles in 1987, Sealand claimed a prior right to its surrounding waters under customary international law, continuing its bizarre existence as an unrecognized entity with its own stamps, coins, and passports.