Closed-circuit oxygen diving in the U.S. Navy.

The pioneers of modern closed-circuit oxygen attack swimming were the Italians. In the early days of World War Two, the Italian Navy found itself lacking the surface warfare power of other nations. In an effort to overcome this deficiency, they developed a cadre of intrepid naval commandos who attacked ships riding on torpedoes and using closed-circuit oxygen underwater breathing apparatuses (UBAs). The Italians had been evaluating these methods of underwater sabotage as early as 1918 (1). Operating against overwhelming odds, these commandos damaged 2 British battleships in Alexandria Harbor in 1941, the HMS Queen Elizabeth and HMS Valiant (2, 3). Later, operating from an Italian tanker, the Olterra, that had been scuttled in 1940 but was later floated and moored in Algeciras harbor, Italian frogmen attacked allied shipping in Gibraltar in 1942/43 and damaged a number of ships (1). British frogmen had a measure of success in this area as well, sinking six Italian ships in Sicily in 1943 and the Japanese cruiser Takao in the Johore Straights (Clark Presswood – personal communication). The biggest British success was the operation against the Tirpitz on 22 Sept 1943 (1). The Tirpitz was one of the most powerful vessels in the German fleet. It was anchored at the innermost end of the 20-mile Alten Fjord in Norway – a harbor protected by nets, mines, and listening posts. Three British mini-subs launched an attack on the harbor– two of the submersibles successfully penetrated the defenses and launched torpedoes. The Tirpitz was not sunk, but was incapacitated for six months. The crews of the midgets were captured. At the start of World War II, the United States Navy had no combat swimmer capability. Diving was performed using the deep-sea hard-hat rig in which the divers were confined to the immediate vicinity of the support vessel. Combat swimming for the purpose of clearing obstacles for an amphibious landing was not a recognized need. At this time, a medical student at the University of Pennsylvania named Chris Lambertsen was designing and building the United States’ first closed-circuit oxygen SCUBA rig. Dr. Lambertsen was a first-year medical student in 1939 when he completed the initial prototype of his Lambertsen Amphibious Respiratory Unit (LARU) (4). He first dove in his LARU prototype in 1940 in Lake Nokomis, near Minneapolis, Minnesota (5) to test the functioning of his new UBA. These were the first closed-circuit oxygen SCUBA dives in U.S. history. About 12 dives were accomplished, including one on which Dr. Lambertsen suffered an oxygen toxicity episode consisting of extremity and diaphragmatic twitching. Although he was tended from the surface, the line was improperly rigged and was dropped by the tender. Dr. Lambertsen managed to return to the surface under his own power (Chris Lambertsen – personal communication). Dr. Lambertsen had a reasonably finished product by the end of 1940. He demonstrated the LARU to the U.S. Navy Experimental Diving