An instructional film that describes the strategic principles and actual practice of Coastal Command's system of convoy protection by anti-submarine patrols as it evolved during World War II. It depicts a wide variety of aircraft and weapon systems, ranging from Spitfires to Sunderlands to Hudsons and Liberators. The impact of surface detection radar (ASV) , as along with the effects of Leigh Light spotlights, convoy formations and patrol lines, is detailed in the war against Nazi Germany's U-boat blockade of the British Isles and key shipping lanes supporting the war in the North Atlantic and Mediterranean.
Original release date: 1944
