On 21 November 1916 the "Britannic" was rocked by an explosion, after hitting a naval mine in the Kea Channel, off the Greek island of Kea. The mines had been put there by the German submarine U-73. A huge explosion tore a hole in the side of the ship which sunk one hour later. The ship was carrying 1,125 people, and nearly all were saved. Two lifeboats were struck by the ship's propellers and 30 people were killed. Bartlett finally stopped the propellers before they could suck in any more lifeboats. Bartlett re-engages "Britannic"’s engines one last time in one final attempt to the island of Kea, pausing the evacuation. At 9 A.M., he ordered the Britannic’s propellers to stop for one final time, and ordered and told everyone it was time leave and evacuate. The lifeboats were launched from the ship. Her final plunge began with her stern beginning to rise from the water, exposing the propellers. Then, as "Britannic" began to slowly dip beneath the surface, survivors from the "Britannic" said they heard what sound is like a tremendous roar or bang coming from the front section of the ship that was already submerged.