During World War II, one of the greatest of the many great challenges facing the Allies was the means of conducting covert underwater reconnaissance and sabotage missions in littoral waters. The Italian Navy, with its special operations 10th Light Flotilla, had spectacularly proved the feasibility of such missions with its manned torpedo attack against the Royal Navy in Alexandria harbor on Dec. 19, 1944, which sank two battleships and a tanker and severely damaged a destroyer. As with all the other new aspects of warfare in that conflict, Allied military leaders knew this was a field of operations in which development of doctrine, design, and construction of equipment, training – in other words, everything – would be a work in progress conducted in the pressure cooker of a shooting war. One person who was not just integral, but invaluable, to the success of Allied covert underwater combat swimming operations was Dr. Christian James Lambertsen.

Lambertsen’s contributions – and here must be stressed the plural – began in World War II and continued for almost four decades. His comprehensive background and experience as a doctor, inventor, and diver made him a unique all-in-one asset; literally the right man in the right place at the right time. His education and research in the new fields of undersea, diving, and hyperbaric (medical use of oxygen at levels greater than atmospheric pressure) medicine coupled with his own diving experience gave him vast empirical and practical knowledge of the physiological effects and dangers of such conditions as oxygen toxicity, hypoxia, prolonged activity underwater at depth, and other dangers. This knowledge, combined with his ability as an inventor, crucially facilitated the development of one of the most innovative self-contained rebreather units ever made, the Lambertsen Amphibious Respiratory Unit. That alone would have secured Lambertsen’s reputation in special operations. But, Lambertsen’s contribution didn’t stop there. He also developed and refined training doctrine, instructed and mentored combat swimmers, and worked on testing and evaluating a one-man submersible canoe designed for special operations, code-named “Sleeping Beauty.” In his long and storied, though covert, career, it’s not an exaggeration to say that Lambertsen “did everything.” It was no surprise, then, that the U.S. Navy SEALs honored him in 2000 with the accolade “Father of U.S. Combat Swimming.”

Lambertsen was born in Westfield, N.J., on May 15, 1917, and grew up in neighboring Scotch Plains. He spent his summers vacationing on the Jersey Shore, and when he was old enough, earned money by helping paint houses for one of his uncles. While in high school, he decided on a medical career. After graduation, he enrolled at a local junior college. Upon receiving his associate degree, he secured a two-year scholarship that allowed him to attend Rutgers University, where he graduated with a bachelor’s of science degree. In September 1939, the same month World War II erupted in Europe, Lambertsen entered the University of Pennsylvania School of Medicine in Philadelphia.

At medical school, he studied respiratory physiology, of which little was known at the time. He conducted numerous experiments studying the effects of hypocapnia (a state of reduced carbon dioxide in the blood as a result of hyperventilation), hypoxia (oxygen deprivation), hypercapnia (an excess of carbon dioxide in the body), and other respiratory conditions. During the summer breaks, he returned to the Jersey Shore, once again to earn money working for his uncle. During the weekends, he put to use the lessons he learned in his medical school research to conduct informal “field experiments.” Together with the help of a couple of cousins, he performed underwater experiments. The first began with the use of a homemade rebreathing rig consisting of a mouthpiece and bag connected to a long hose that was attached to a bicycle pump. The cousins would operate the pump, providing fresh air to Lambertsen as he swam underwater. This awkward (and no doubt for the cousins, tiring) system was soon replaced by a cylinder of compressed oxygen. This system proved unsatisfactory due to the accumulation of carbon dioxide in his air bag. Shortly thereafter Lambertsen learned of a new type of anesthesia equipment that used a carbon dioxide absorbent to solve the accumulation problem. Encouraged, Lambertsen fashioned a small carbon dioxide scrubber that fit between his mouth and the breathing bag. Though the arrangement was crude, it worked.

Lambertsen had kept Dr. Henry Bazett, his physiology professor, informed of his work. Bazett responded with enthusiasm and contacted Cleveland-based Ohio Chemical and Manufacturing Company, a maker of anesthesia equipment, informing them of his student’s work and requesting additional parts. Ohio Chemical instead offered Lambertsen a job during the summer of 1940 at the then-princely salary of $30 per week. After a meeting with the company’s president, J.G. Sholes, it was mutually decided that Lambertsen’s task during the summer would be to move to Minneapolis, Minn., where the company had a plant manufacturing anesthesia equipment, and there work on an underwater breathing device that could be used in lifesaving.

The result was a 12-pound, semi-closed pendulum rebreather equipped with a 40-liter oxygen bottle and a carbon dioxide scrubber. Lambertsen conducted underwater experiments at Lake Nokomis, near Minneapolis, and later at Lake Erie, near the company’s main office. Lambertsen performed the underwater tests himself and discovered that he could do about a half-hour of light work down to a depth of 60 feet. The success of these tests caused Lambertsen to suggest to Sholes that the apparatus might be useful for miners trapped in passages containing hazardous atmospheres. Excited by the idea, Sholes ordered a gas-tight chamber constructed on a loading dock where they could conduct a hazardous atmosphere demonstration. Inside the large airtight wood and Plexiglas® structure were a canary, a dog, and Lambertsen, who was wearing his rebreather. The chamber was flushed with carbon dioxide to remove all oxygen, and then filled with cyclopropane, a highly flammable anesthetic gas, to simulate underwater conditions. The audience in attendance included newspaper and newsreel reporters, police and fire department units, as well as company officials.

After a few minutes, the canary fell unconscious. Not long after that, the dog dropped to the floor, also unconscious. It was about 20 minutes into the demonstration that Lambertsen leaned down to check on the dog. When he did so, he too fell to the floor unconscious. The firefighters immediately used their axes to break open the chamber and rescue the occupants. An examination of Lambertsen’s rebreather revealed that the cyclopropane had slowly penetrated the breathing bag’s latex shell.

News of the demonstration was circulated throughout the nation because at that time, use of an artificial breathing device for 20 minutes “underwater” was an extraordinary achievement. By the time Lambertsen returned to Philadelphia to continue his studies, he was a celebrity. Bazett was thrilled, writing to the Journal of the American Medical Association: “The equipment was successful because it was designed by a man who studied the physiological principles carefully and is capable not only of testing it himself but training the users. It could not have been developed by a physiologist unfamiliar with the practical side nor by a swimmer without physiological training.” More importantly, Bazett, a British citizen, felt Lambertsen’s device had military applications. He sent a letter to the British Admiralty, writing, “The apparatus has advantages in lightness and freedom of movement in the water making it adaptable either for use of underwater troops of the trouble-making type or for night-raiding enemy defenses.” Bazett also arranged for a demonstration for the U.S. Navy conducted in Washington, D.C., for the Navy Experimental Diving Unit (NEDU) in January 1941. Though the demonstration was successful, the Navy passed on his device. Even so, Lambertsen received encouragement from Lt. Al Behnke, a junior medical officer who witnessed the demonstration. Crucially for the future of special operations frogmen, Lambertsen came away with a firm belief that the future for his apparatus lay with the military – and that he would have to do a major redesign.