The legendary horror and science-fiction actor recently passed away. But before he ever played Count Dracula or Count Dooku, Christopher Lee was one of England’s most daring soldiers.

As Adolf Hitler’s forces stormed across Europe in the lead-up to World War II, Lee volunteered to fight for the Finnish in 1939 and eventually enlisted in the Royal Air Force. He spent the war years learning Russian, German, and French, fought Mussolini’s forces in North Africa, was nearly killed twice, and even managed to subvert a mutiny. His many acts of bravery on the battlefield netted him several honors.

But Lee’s military career took a strange turn as the global conflict began winding down. Due to his prolific language skills, he was an obvious pick to serve in the Central Registry of War Criminals and Security Suspects, an organization was tasked with hunting down fleeing Nazis who had committed unspeakable crimes. Due to the sensitive and secretive nature of the registry, not much is known about what Lee and his colleagues did during this period. He often refused to talk about it and, when pressed during interviews, he would routinely say to reporters: “Can you keep a secret? Well, so can I.”

Nevertheless, at least a few stories slipped out. Lee often hinted that the missions he participated in. On the set of one of The Lord of the Rings movies, director Peter Jackson attempted to tell Lee how to behave during a scene in which his character was struck by a dagger. After patiently listening to Jackson’s instructions, Lee coolly informed him, “Have you any idea what kind of noise happens when somebody’s stabbed in the back? Because I do.”

In 1946, Lee returned to the U.K. and eventually decided to become an actor. His language skills and his unflappable persona aided him greatly in the decades that followed. “When the Second World War finished I was 23 and already I had seen enough horror to last me a lifetime,” he once said. “I’d seen dreadful, dreadful things…so seeing horror depicted on film doesn’t affect me much.”