World War II started on September 1, 1939, when German troops invaded Poland. The Soviets also invaded Poland on September 17, 1939, from the east. In August 1939, Germany and Russia signed a non-aggression pact, which did not last throughout the war. Great Britain entered a military alliance with Poland 2 days after the non-aggression pact was signed. The Germans used a new type of battle strategy, called "Blitzkrieg", or lightning war. 5 German Armies invaded Poland with about 1.5 million men, 2,000 tanks, and 1400 modern aircraft. Poland still managed to maintain small cavalry squadrons to fight the enemy during the invasion. By September 25, 1939, about 1,150 bombs were dropped over Warsaw, Poland.
By the end of September 1939, nearly 20,000 Poles had been killed. More than a million Poles had been deported to labor camps in the Soviet Union. In October 1939, a German U-boat managed to penetrate the defenses of the main British Naval Base. In November, some 450,000 Soviet Union troops started a brutal, frozen battle called the Winter War with Finland, Lithuania, Estonia, and Latvia. In December 1939, the German submarine Graf Spee was damaged by the British Royal Navy.
By early 1940, Germany and the Soviet Union had divided control over Poland, and Finland surrendered to the Soviet Union in January. After the invasions in 1939, Germany simultaneously invaded Noway and Denmark in April. By May, Germany had invaded Belgium, the Netherlands, Luxembourg, and the lightly defended Ardennes Forest north of the Maginot Line. Germany's Air Force attempted to destroy the British Royal Air Force, but failed because they were greatly out-numbered.
The USS Arizona (BB-39) was a US battleship that was bombed during the attack on Pearl Harbor. The US had hoped to stay out of the war, until this attack happened. Congress declared war on Japan in 1941 after the attack. President Roosevelt and Prime Minister Churchill decided to focus on Hitler first, than Japan. Hitler's main goal was to dominate the Mediterranean countries.
World War II Timeline - Remembering Pearl Harbor @ Nationalgeographic.com. Web. 23 Apr. 2017.
Hickman, Kennedy. "Road to Conflict: The Causes of World War II." ThoughtCo. Web. 23 Apr. 2017.
History.com Staff. "World War II History." History.com. A&E Television Networks, 2009. Web. 21 Apr. 2017.
"Start of World War II: September 1939-March 1940." HowStuffWorks. 06 Sept. 2007. Web. 20 Apr. 2017.
Taylor, Alan. "World War II: The Invasion of Poland and the Winter War." The Atlantic. Atlantic Media Company, 26 June 2011. Web. 20 Apr. 2017.
"United States History." World War II. Web. 23 Apr. 2017.
"World War II." HistoryNet. Web. 20 Apr. 2017.
"World War II Beginning 1939: Germany Invades Poland 75th Anniversary." Time. Time. Web. 21 Apr. 2017.
"World War II." Britannica School, Encyclopædia Britannica, 30 Sep. 2015. Web. 28 Apr. 2017.