The Battle of the Atlantic (1939-1945) was one of the most crucial of World War II; tens of thousands of sailors were killed on each side, and German U-boats almost succeeded in choking off the supply lines on which Britain's survival depended. This hard-fought conflict gets an engrossing retelling in this companion to the History Channel series. Williams, producer of War Crime: Five Days in Hell for the BBC, covers every aspect of the cat-and-mouse game in which U-boats stalked merchant convoys across the ocean and were in turn hunted by Allied planes and destroyers. It's a harrowing tale, full of torpedo attacks, depth-chargings and drownings in the icy North Atlantic, and Williams draws on many first-hand accounts, both German and Allied, to bring it to life. He also pulls back to examine the strategic dimensions of the battle, exploring the development of German wolf-pack tactics, the initially bumbling Allied efforts to organize convoys and escorts, and the increasingly sophisticated anti-submarine warfare techniques that eventually drove the wolf packs from the North Atlantic. Williams is especially good at explaining the vital development of sonar, radar, detection and decryption technologies that enabled Allied escorts to locate, evade and destroy the stealthy U-boats with ever greater success. The conflict was both a nerve-wracking battle of wits and an epic of self-sacrifice, and Williams's thorough research and skillful storytelling does it full justice.