enter the war in Europe. Before Germany and Italy declared war on the nation, President Roosevelt had many meetings with Winston Churchill, who was imploring him to bring US force to the European theater to help shorten the war.

Nevertheless, there are similarities between the two theaters. The war in both territories was difficult and deadly for the US. Unlike Germany, which had a large group of trained soldiers, the Japanese army had a small corps of officers who were professional military men. Most of the soldiers were relatively inexperienced. Even so, while the Japanese military might not have been as skilled or well-equipped as the German army, the Japanese fought aggressively.

Racial conflicts underpinned both fights. The war in Europe was launched by the German notion that German Aryans were superior to other peoples. The war in the Pacific was launched by the Japanese and also had racial overtones on both sides, although they might have been more nuanced.

Both theaters involved several countries. In the Pacific theater, the war was led by the Japanese against US and British territories. Moreover, the Japanese were fighting in partnership with the other Axis powers, Germany and Italy. In the European theater, the German-led fight encompassed military launches against Poland, France, Russia and many others. Similarly, the Germans were in agreement with the other Axis powers, Italy and Japan.

The war in both territories concluded when the Axis fighters were overpowered by the Allied forces. The war in the Pacific ended with the detonation of the atomic bomb, while the Nazis eventually were overcome by the approaching Russian and US military forces.

In the European and the Pacific theaters, the United States faced a well-trained, well-disciplined, and initially well-equipped enemy. Both the Japanese and to a somewhat lesser extent the Germans (many of whom, by the end of the war, were conscripts) were fanatically devoted to their cause and reluctant to surrender. This was especially true of the Japanese, who had a strong cultural bias against surrender, which made them both difficult to defeat and especially brutal toward American captives. Strategic air power was important in both theaters, as the Allies reduced almost every major city in Japan and Germany to rubble before finally forcing surrender. Indeed, the Japanese were forced to surrender by the devastating might of American air power without the necessity of a ground invasion. Obviously the Pacific war was more of a naval war, but both theaters witnessed massive amphibious assaults on such beachheads as Anzio, Normandy, Saipan, and Iwo Jima. Some of the city-to-city fighting that characterized the conquest of France and Belgium was also witnessed in the Philippines. Obviously, there were many differences between these two conflicts—World War II for the United States was in reality two different wars—but in terms of human loss and the amount of military power that had to be brought to bear in order to achieve victory, they had much in common.

Although the fighting took place simultaneously, the European theater and the Pacific theater of World War II had significant differences. In Europe, more nations were engaged with each other. On one side, Germany, Italy, and their puppet states faced off against the Soviets, Americans, Canadians, and British. This required more coordination between nations and the establishment of multi-national command structures. In some cases, such as the invasion of Normandy, the forces of several nations fought alongside each other. The Soviets on the eastern front were in charge of their own forces. However, after the Allies gained a foothold in Western Europe, it became necessary to coordinate the operations along that front through an organized command structure. Ultimately, General Eisenhower, an American, was designated as the "Supreme Allied Commander." The war in the Pacific, other than the fighting in mainland China, was mostly a conflict between Japan and the United States. Although Australia, New Zealand, and the British were involved to a certain extent, the United States conducted most of the fighting against the Japanese. Therefore, a complex multi-national command structure like the one in Europe was not necessary.

Geography also played a large role. The war in Europe was primarily fought on land. Both the Axis and Allies fought to capture and control land. The land itself was diverse, ranging from open deserts to alpine mountains, farmland, and forests. Fighting took place in cities and the countryside alike. This diversity in landscape put the focus mostly on infantry tactics. Air, armored, and naval forces supported the infantry, but it was soldiers with boots on the ground who did most of the fighting. The Pacific theater of the war was fought largely at sea and on small, far-flung islands. As a result, naval and air power became much more important. The use of battleships and aircraft carriers defined much of the combat in the Pacific. Soldiers fought on islands, where the landscape and tropical diseases often became as much of a threat as the enemy.

While the Germans were certainly capable of war crimes and atrocities (and did commit them frequently), they were more of a traditional enemy for the Allies. The Germans were also technologically proficient. The Allies in Europe had to face off against superior tanks, airplanes, and even ballistic missiles. The Japanese were not as technologically advanced as the Allies. Their technological deficits included a lack of radar and long-range bombers. However, they made up for this by being tenacious fighters, who usually fought to the death instead of surrendering.

There were differences in command structure for sure.  In Europe, the US and the British had to share command with, for example, Eisenhower and Montgomery disagreeing with one another quite regularly.  By contrast, the Pacific was completely an American show.  There was no real need to coordinate with Allies in that theater.

Another major difference was the sort of weapons that could be brought to bear.  The European theater was influenced strongly by tank warfare on the plains of Europe.  By contrast, the Pacific theater offerred very little in the way of open spaces.  Fighting in the Pacific was much more reliant on infantry and was done in jungle to a large extent.

In addition, the enemy was very different.  The Germans were much more of a traditional enemy who would do things like surrendering.  By contrast, the Japanese defended so unrelentingly that very few Japanese defenders survived battles like those on Saipan and Iwo Jima.  This made for a very different fighting experience.

There were many important differences between the war in Europe and the war in the Pacific. Obviously, the first difference was in the terrain. The war in Europe was fought primarily on land. Yes, there was submarine warfare and naval blockades and crossing of rivers and the Mediterranean Sea and of the Atlantic Ocean. But the war in the Pacific was dominated by the huge expanses of water that had to be crossed, on the water or by air, in order to engage the enemy.

Weather was another variable that affected the two theaters differently. Over the stretch of the war, those fighting in different areas of Europe experienced weather ranging from summer in the Sahara Desert to winter outside Moscow or St. Petersburg. The conditions challenged men and equipment, both directly and in terms of medical complications caused by cold, heat, precipitation of all kinds, etc. In the Pacific, the weather caused different kinds of challenges as fighting took place under tropical heat and humidity with the presence of health complications related to that part of the world.