Answer:
The Second World War, from 1939, to 1945, became a major world conflict as it virtually affected all the continents around the globe. What first started as merely a confrontation of interests between European nations, this soon changed as Hitler, and his allies, continued ravenously attacking and advancing, threatening now not just Europe, but the entire planet. One such ally that really became troublesome and dangerous, but in the Pacific front, was Japan. Given that this has multiple questions, the answers are as follows:
1: The Atlantic Charter was a declaration made between the leaders of the U.S and the U.K, the main, and most powerful of the Allied group, against Germany, Italy and Japan, and it took place on 14th August, 1941. It literally established the steps that both nations foresaw for themselves and the world in a post-war scenario. It set the goals, but also the limits and boundaries that would be born thenceforth.
2. The attack on Pearl Harbor, which happened in 1941, and which led to the U.S finally entering the Second World War, happened because Japan wished to attain certain territories in the Pacific and wished to expand its power. The U.S, with its naval base in Pearl Harbor, was a threat to their plans. So, while Japan conned the U.S into believing that they wanted peace, they prepared a sneak attack on the base, destroying almost all of the Pacific Fleet.
3. After the attack, President Roosevelt declared war on Japan on December 8, 1941 and by December 11, 1941, Germany, Italy and the Axis powers, had declared war on the U.S. Roosevelt, with the full agreement of Congress and the American people, began to establish financial policies to raise the money for war, gather the U.S´s military power, recruitment of men and deployment both towards the Pacific front and the European scenario.
4. Fighting on different fronts affected all countries involved because it divided their strength and forces. As such, military strategist would focus on establishing mechanisms of attacking the weaker sides of forces to break through them. This is what happened with Germany, for example. They opened too many major fronts: in North Africa, western Europe and in Russia, and in the end, their forces were spread too thin and could not withstand the attacks of the unified Allies.
5. The Battle of the Bulge, also known as the Ardennes Counteroffensive, took place between 1944 and 1945 and it helped to end the war because at this point, Germany, in an almost desperate last effort, sent all of its might to end the conflict on the western front. However, the military power of Germany was already exhausted, and this caused break points through which the Allies were able to start pushing the Germans back and defeating them.