For almost a century, the sinking of the RMS Lusitania has remained shrouded in secrecy. The Cunard liner was torpedoed on May 7, 1915, by the German submarine U-20 while steaming from New York to London.
It sank in 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 among the victims.
Since the day the Lusitania went down, some experts have blamed the British for the high loss of life, claiming that they illegally stowed a cargo of high explosives on board, concealed as cheese or casks of beef on the ship's manifest.
The explosives were said to have caused a second, larger blast after the impact of the torpedo, causing the 790ft liner to sink rapidly before help could arrive.
But now scientific research has debunked these theories.
The researchers sent a camera 20ft into the wreck, which lies at a depth of 300ft, to inspect the cargo hold and blast damage. They then conducted tests at the Lawrence Livermore National Laboratory, in California.
They analysed the various theories: that the second explosion was the result of aluminium, which was used to make landmines, and gun cotton, an artillery propellant.
They found the appearance of an aluminium explosion was very different to that reported by survivors, while gun cotton would have exploded instantaneously, rather than after a delay of 15 to 20 seconds.
Instead, they concluded the second blast was a boiler explosion, which did not itself cause significant damage. The rapid sinking, they concluded, was simply due to damage caused by the torpedo strike.