Consider, for example, the absolute necessity of getting men and supplies across the Atlantic Ocean. Absent this, it would have been impossible to supply the Russians and to accumulate the men and materiel that were necessary for the D-Day invasion. By early 1943, the U-Boats were enjoying their greatest success of the war in sinking Allied shipping. So great was the crisis that, according to Kennedy, British imports that year were less than they had been in 1939. But by that summer, the Allies had made a number of strategic and tactical changes that gave them a decisive edge in the North Atlantic.
The advances themselves – long-range and better equipped bombers to provide adequate air cover for the convoys; improved radar developed by university scientists in England and the United States; a new mortar that began as a “quirky schoolboy’s dream” but became an effective anti-submarine weapon; and the creation of far more effective naval escorts to combat the German U-boats – seem to be little more than incremental changes. But they stemmed from experience and the application of analysis to problems that needed to be solved. And taken together they became the key factors in winning the Battle of the Atlantic.
Kennedy analyzes several other problems in the same way: gaining control of the skies over Europe and Japan, blunting the speed and power of the German blitzkrieg, successfully invading enemy held territory, and fighting wars over vast distances. In every case the specific strategies and tactics differed but the common thread is the ability of Allied engineers, technicians and scientists to devise solutions that directly affected the field of battle.