After the shipping of the heavy water equipment to Germany, the last of the heavy water, about 400 kg in 40 drums of water of varying purity, were to be shipped from Ryukan. In February 1944 London was informed by the Norwegian underground. MI6 and SOE recommended sabotage, the Norwegian High Command and government consented. Men in the Resistance received the final order, the railway freight cars and the ferry Hydro carrying them were to be sunk in the deep waters of Lake Tinnsjø. The heavy water had to be destroyed, at the risk of reprisals. London had ordered one Milorg resistance group to blow up the ferry, and without advising this first group had also ordered another group to blow up the train that would be carrying the freight cars south. In addition the RAF had orders to bomb the ship carrying the heavy water from Norway to Germany. The night before the actual transport 2 men of the Milorg sneaked into the unguarded ferry, placed 19 pounds of explosive at the stern of the ferry and then split up and made their way, one to Sweden the other back to his contact point. The bomb exploded at 1045 hours on Sunday Feb. 20, as the ferry was over the deepest part of the lake. As ferry tilted down by the bow, the freight cars wrenched free from their tethering lines and sank in a couple minutes into 1300 feet of water. 14 civilians and 4 soldiers lost their lives, 29 were rescued, including the Hydro's Captain Sørensen and four German servicemen. Four of the containers with heavy water reached the surface and probably reached Germany. In case the sabotage failed, another group of saboteurs were ready further down the valley and in the North sea, British submarines waited.
(Alex Gordon)