How One British Chemist Used a Purgative Oil to Sabotage 40 Nazi Atlantic Submarine Crews

In 1941, while German U-boats dominated the Atlantic, a quiet British chemist named Charles Fraser-Smith developed an unexpected weapon: contaminated olive oil. Working from a London laboratory, he crafted a plan so audacious yet invisible that it would subtly undermine one of the Third Reich's most formidable military forces. Using croton oil—an extreme purgative—diluted into Spanish olive oil, Fraser-Smith orchestrated one of WW2's most ingenious acts of sabotage. The contaminated supplies reached German naval bases at Brest and Saint-Nazaire, incapacitating U-boat crews during critical operational windows. Over nearly two years, 40 separate illness outbreaks delayed patrols and disrupted schedules—all while German intelligence couldn't explain the mystery. This is the untold story of how one man's chemistry set helped keep Britain's lifeline open, and why sometimes the most effective weapons are invisible. #WW2History, #BritishIntelligence, #UBoatWar, #SecretWeapon, #CharlesFraserSmith, #BattleOfTheAtlantic, #WW2Documentary, #MilitaryHistory,