For almost a century, the sinking of the passenger liner RMS Lusitania has remained shrouded in secrecy, with claims that the British bore some of the responsibility for the disaster by hiding a secret cargo of high explosives on board.

But new research has established the facts behind vessel's loss and cleared the British government of the charges against it.

The Cunard liner was torpedoed on 7 May 1915 by a German submarine, U-20, while on route from New York to London. It sank in just 18 minutes, eight miles off the coast of Ireland, with the loss of 1,198 civilian lives. Most of the dead were British although 114 Americans were also killed....