1941, the Japanese navy attacked Pearl Harbour. The attack on Pearl Harbour knocked out several key US battleships and killed 2,403 Americans. The following day, FDR, in his now infamous “Infamy Speech” to Congress, called for war to be declared on Japan, with congress declaring war on Japan that same day, and Germany and Italy 3 days later. The scale the tragedy that struck caused antiwar sentiment to disappear. The Japanese empire would extend its borders up until June 1942, when the American navy was able to permanently halt their progress at the Battle of Midway. The Battle of Midway proved to be the first round in a series of slow, difficult, and costly island hopping. This was all in efforts to gain bases from which the airforce could wreak havoc on the Japanese. Roosevelt opted to stay out of the tactical military decision making, something his counterpart in Germany relished. By late 1944, most specifically the Battle of Leyte Gulf, the Americans had not only recaptured much of the territory lost, but also dealt the final blow to the Japanese navy.

The events that took place in Europe were much more straightforward. In January 1943, at the Casablanca Conference, it was decided that the Allies would defeat the Axis forces in North Africa before any incursions onto mainland Europe. By May 1943, the North African campaign was over, with over 250,000 axis soldiers taken as prisoners. The Allied invasion of Sicily was launched that June, and mainland Italy in September. FDRs attention was now turned to France, where he selected General Dwight D. Eisenhower to command the invasion. Eisenhower opted to invade Europe on June 6th, 1944. Operation Overlord as it was to be named consisted of the largest naval force ever assembled, allowing the Allies to break the Atlantic Wall and successfully land in Normandy. With the Germans fighting a war on two fronts, and the seemingly endless stream of US arms and supplies, the allies were able to slowly liberate more territory from occupation.