In 1942, as Nazi U-boats threatened Britain's survival, Winston Churchill greenlit one of history's most outlandish military projects - building massive aircraft carriers made of ice. Project Habakkuk proposed creating unsinkable 2,000-foot vessels by mixing ice with wood pulp to create "pykrete," a bizarre material that was bulletproof, slow to melt, and could be repaired mid-ocean using seawater. The eccentric British inventor behind the plan famously demonstrated pykrete's potential by shooting a block of it in front of shocked Allied commanders - nearly killing an admiral with the ricocheting bullet. Engineers built a prototype on a Canadian lake, and the full-sized ships would have been larger than the Titanic, carried 200 aircraft, and had 40-foot thick hulls impervious to torpedoes. Discover why this seemingly absurd frozen fleet was serio ...