From the thesis abstract: "At the outbreak of World War II, Great Britain was unprepared to counter German submarine warfare in the Atlantic. In World War I, Germany had conducted a devastating U-boat campaign against merchant shipping, threatening the Atlantic supply chain that Britain depended on for goods, food, and materiel. The Royal Navy defended the commercial fleet by organizing convoy escorts. In the interwar period, the navy was burdened by a poor economy, interservice rivalry, and a treaty limiting its fleet. Historian Correlli Barnett points out that the admiralty had warned that the diminished navy was unprepared to face the rising aggression of Japan and Germany in his book Engage the Enemy More Closely, published in 1991 by Norton. When war was declared, the navy immediately resumed the convoys and escorts, but it was not sufficient to protect all routes. In the end, technological advances, above all the introduction of long-range aircraft in an antisubmarine role, helped offset British unreadiness and concomitant losses in the Atlantic, but ingenuity would not have been enough. Without strategic alliances, Britain could not have gained the upper hand."
Naval Postgraduate School, Dudley Knox Library: http://www.nps.edu/Library/index.aspx