Channel convoys and North Sea ports face repeated mine-laying

Duffy follows transatlantic reinforcement traffic into the English Channel and onward to North Sea ports serving Belgium, the Netherlands, and West Germany. Concentrated shipping in restricted waters offered the Warsaw Pact targets for submarine and air attack as well as minefields laid by either platform. Clearance was not a one-time task because later missions could reseed the same approaches. North Sea allies were modernizing escorts and mine-countermeasure vessels, but might have too few, especially if West German ships were diverted to Baltic mine-laying. Britain alone was working on deep-water clearance, with only twelve new trawlers being fitted for a mission whose technology remained largely unproven.