Unit 731: Firsthand Accounts of Japan's Wartime Human Experimentation Program

by Hal Gold

When the planes landed, they came alongside their mother ships, and they were hoisted back aboard with winches. The I-400 submarine, the only ship of its class, was a large sub capable of carrying three planes. This boat was earmarked for the attack on America’s west coast. The sub had a displacement of 3,530 tons, an underwater speed of six and a half knots, and a surface speed of eighteen knots. It was diesel-powered and snorkel-equipped, so that its combustion engines could run even while the boat was submerged. This characteristic enabled it to use one of its two engines for propulsion, while it charged its batteries with the other. At sixteen knots on the surface, it had a normal range of thirty-one thousand nautical miles. Its range could be extended by filling the ballast tanks with fuel oil instead of water. Filling the ballast tanks would, of course, mean that the sub could not surface until after a sufficient amount of fuel had been consumed, but Allied air and naval presence in the Pacific in the early part of 1945 would make submerged travel prudent at any rate. Reaching the American mainland seemed to be no problem, at least as far as technology was concerned.