During World War II when the Home Fleet warships of the Royal Navy temporarily left Scapa Flow after the sinking of H.M.S. Royal Oak, many ships were based at the Tail of the Bank, on the Clyde. The Clyde Anchorages Emergency Port was initiated in September 1940, by shipping companies that had been evacuated from the Royal Docks (after the first bombing raids on London). The Upper Firth was protected by an anti-submarine boom stretching from Cloch Point, across the Firth, to Dunoon, making it a secure anchorage and hundreds of merchant ships of the Atlantic convoys and ships of the Free French navy gathered there as well.