The second volume of Hunters and Killers begins with the early 1943 turning point of World War II's Battle of the Atlantic, when Allied efforts forced the U-boats to be withdrawn from the North Atlantic.
With growing numbers of escort (jeep) aircraft carriers and very-long-range patrol aircraft, coupled with cryptologic breakthroughs and new weapons, the Allied anti-submarine advantage mounted even more quickly.
The Germans attempted to counter these setbacks by introducing the snorkel, increasing new submarine construction, and developing revolutionary submarine designs, especially the highly-effective Type XXI. Nonetheless, the highly-organized Allied ASW defense of the Normandy invasion against U-boats in June 1944 completely thwarted the German submarine attempt to disrupt the Allied assault on Nazi-held Europe, and from then until the end of the war the Germans suffered what could only be called a "U-boat Armageddon." In the Pacific, the Japanese never mounted an extensive, German-style anti-shipping campaign against the Allies, whereas U.S. submarines became highly effective against the Japanese in that same role. Because U.S. ASW efforts in the Pacific borrowed heavily from anti-submarine developments for the Atlantic theater, much of the technical discussion covers Japanese ASW, which, while not particularly effective, showed some interesting innovations - and succeeded in sinking almost 40 American boats.
Subsequently, the 45 years of the Cold War became in large part a non-shooting confrontation between NATO and Russian submarines, while opposing ASW forces added their own weight to the balance. The deployment of submarines carrying strategic, nuclear-armed missiles on both sides intensified the submarine threat, and a new generation of platforms, sensors, and weapons was developed to counter it. Of these, perhaps nuclear ASW weapons and undersea surveillance systems, such as the U.S.
SOSUS, were most significant. Finally, the extensive submarine/anti-submarine aspects of the Cuban Missile Crisis and the Falklands War are discussed. This second volume of Hunters and Killers concludes by describing the state of the world's ASW in the early 21st Century, while drawing a series of "lessons learned" from the evolution and practice of ASW over the last one hundred years. There is no "golden bullet," but the central importance of numbers, persistence, and responsive technology remains.