It has been called the “silent service.” Since their introduction in the early 20th century, service aboard submarines has been among the deadliest military occupations, with a full 70% of German U-boat crews during WWII never returning from patrol. But the hazards faced by submariners go well beyond enemy guns, depth charges, and torpedoes; submarines are complex machines operating in an extremely hostile environment, and can prove just as deadly in peacetime as in war. So the crew of the British submarine HMS Thetis was to discover in June 1939 when a seemingly routine shakedown cruise ended in tragic accident where Murphy’s Law was proven an immutable rule of the universe. (By the way, if you’ve not seen our video on Who was the Murphy in Murphy’s Law, we strongly suggest you go watch it. Go ahead, we’ll wait. The man behind it, Dr. John Paul Stapp, is the unsung hero and saver of millions of lives since his incredibly badass work and balls of solid steel did what he did to give us Murphy’s Law.)