The British were involved in WWII, their main combatant being Germany. As international law states, building forts in international waters is illegal. Despite the law, Britain had to take desperate measures, and therefore built sea forts for defense. Although one fortress named Roughs Tower was originally supposed to be built in the territory of England, it was instead placed in international waters, specifically the North Sea. It was about 7 nautical miles from the British coast, exceeding the 3 mile limit to build forts. Roughs Tower was built of concrete and steel. This fort was no longer used by the British army by the 1950's. It did not get taken down, although Britain should have obeyed the international law about building forts. Although many forts got demolished after the war, Roughs Tower remained standing. Since the fort did not belong to any territorial waters of any nation, it was lawfully not part of any country.
A man named Roy Bates had previously owned a radio station called "Radio Essex", which was located in an abandoned fortress in British territory. These types of stations were called "pirate stations" and were adored by the general public. Bates, having battled the government over "Radio Essex", decided to escape British control by declaring ownership of Roughs Tower. He claimed the fort in the Christmas Eve of 1966. The birth of the Principality of Sealand was on September 2nd, 1967. This was the first time the new flag of Sealand was raised. Friends, family, and followers of Roy Bates witnessed the beginning of this independent nation. As a birthday gift, Bates had given his wife the title of "Princess Joan", a very romantic and thoughtful gift.