Kepangeranan Sealand

Pada 1943, selama Perang Dunia II, HM Fort Roughs dibangun oleh Britania Raya sebagai salah satu dari Benteng Maunsell, terutama untuk pertahanan
terhadap pesawat mine-laying Jerman yang
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penting; it comprised a floating pontoon base with a superstructure of two hollow towers joined by a deck upon which other structures could be added. The fort was towed to a position above the Rough Sands sandbar, where its base was deliberately flooded to allow it to sink to its final resting place on the sandbar. The location chosen was approximately 7 nautical miles from the coast of Suffolk, outside the then three-mile territorial water claim of the United Kingdom and therefore in international waters. The facility (called Roughs Tower or HM Fort Roughs) was occupied by 150–300 Royal Navy personnel throughout World War II; not until well after the war, in 1956, were the last full-time personnel taken off HM Fort Roughs.