Another classic article from Damn Interesting:
From his personal effects, the man was identified as Major William Martin, a temporary captain and acting major in the British Royal Marines. Rather than allowing possible military intelligence to go unintercepted, the local agents for the Abwehrâ€“ the German intelligence organizationâ€“ coaxed the briefcase open to examine its contents. Inside, along with the man’s personal effects, the Nazis discovered a personal correspondence between Lt. Gen. Sir Archibald Nye, vice chief of the Imperial General Staff, and General Sir Harold Alexander, the British commander in North Africa. This letter described key details of the Allies’ plans to invade Nazi-held territory. It seemed that luck was favoring Germany; but the discovery ultimately resulted in disaster for the Nazis.