The First World War convoy decision created an escort crisis

The First World War failure differs from the familiar claim that the Royal Navy entered the Second World War without preparing for submarine attack. British escort construction began before the Second World War, arguably in the late 1920s, whereas First World War planners initially treated submarines as weapons for fleet-on-fleet action. They also expected the laws and conventions of war to restrain attacks on merchant shipping, so there appeared to be no need to convoy ships and therefore no requirement for a mass of convoy escorts. The passage credits a paper by Henderson with helping Jellicoe press politicians to adopt convoying once unrestricted attacks made the existing assumptions untenable. As soon as the convoy decision was taken, the escort shortage became an immediate shipbuilding problem.