(CNN) Here's a look at World War II, which lasted from 1939 to 1945.
The Peace of Paris - The treaties worked out in Paris at the end of World War I satisfied few. Germany, Austria and the other countries on the losing side of the war were especially unhappy with the Paris Agreement, which required them to give up arms and make reparations. Germany agreed to sign the Treaty of Versailles only after the victorious countries threatened to invade if Germany did not sign it. Germany made the last payment on reparations in 2010.
Economic Issues - World War I was devastating to countries' economies. Although the European economy had stabilized by the 1920s, the Great Depression in the United States led to economic downfall in Europe. Communism and fascism gained strength in the wake of economic problems.
Nationalism - An extreme form of patriotism that grew in Europe became even stronger after World War I, especially for countries that were defeated.
Dictatorships - Political unrest and unfavorable economic conditions lead to the rise of dictatorships in countries such as Germany, Italy, Japan and the Soviet Union.
Failure of Appeasement - Czechoslovakia had become an independent nation after World War I, but by 1938, was surrounded by German territory. Hitler wanted to annex the Sudetenland, an area in western Czechoslovakia where many Germans lived. British Prime Minister Neville Chamberlain wanted to appease Hitler and agreed to his demands for the Sudetenland after Hitler promised he would not demand more territory. Hitler seized the rest of Czechoslovakia in March of 1939.
Germany, Japan and Italy formed a coalition called the Axis Powers. Bulgaria, Hungary, Romania and two German-created states--Croatia and Slovakia--eventually joined.
Major Players:
Germany - Adolf Hitler, Der Fuhrer
Japan - Admiral Hideki Tojo, Prime Minister
Italy - Benito Mussolini, Prime Minister
The United States, Great Britain, China and the Soviet Union made up the Allies, the group fighting the Axis. Between 1939 and 1944 at least 50 nations would eventually fight together. Thirteen more nations would join by 1945 including: Australia, Belgium, Brazil, British Commonwealth of Nations, Canada, India, New Zealand, South Africa, Czechoslovakia, Denmark, France, Greece, Netherlands, Norway, Poland, Philippines and Yugoslavia.
Major Players:
United States - Franklin D. Roosevelt, President
Great Britain - Winston Churchill, Prime Minister
China - Chiang Kai-Shek, General
Soviet Union - Joseph Stalin, General
16,112,566 - Number of US troops that served in the conflict.
670,846 - Number of US wounded.
Battle: 291,557
Non-Battle: 113,842
Total In-Theatre: 405,399
Australia: 23,365 dead; 39,803 wounded
Austria: 380,000 dead; 350,117 wounded
Belgium: 7,760 dead; 14,500 wounded
Bulgaria: 10,000 dead; 21,878 wounded
Canada: 37,476 dead; 53,174 wounded
China: 2,200,000 dead; 1,762,000 wounded
France: 210,671 dead; 390,000 wounded
Germany: 3,500,000 dead; 7,250,000 wounded
Great Britain: 329,208 dead; 348,403 wounded
Hungary: 140,000 dead; 89,313 wounded
Italy: 77,494 dead; 120,000 wounded
Japan: 1,219,000 dead; 295,247 wounded
Poland: 320,000 dead; 530,000 wounded
Romania: 300,000 dead; wounded unknown
Soviet Union: 7,500,000 dead; 5,000,000 wounded
United States: 405,399 dead; 670,846 wounded
About 70 million people fought in the armed forces of the Allied and Axis nations.
Finland never officially joined either the Allies or the Axis and was at war with the Soviet Union at the outbreak of World War II. Needing help in 1940, the Finnish joined forces with Nazi Germany to repel the Soviets. When peace between Finland and the Soviet Union was declared in 1944, Finland joined with the Soviets to oust the Germans.
Switzerland, Spain, Portugal and Sweden declared neutrality during the war.
The Soviet Union lost the most soldiers, in excess of seven million.
The number of civilian casualties in World War II may never be known. Many deaths were caused by bombing raids, massacres, starvation and other war-related causes.
Six million Jewish people died in Nazi concentration camps during the war. Also killed were hundreds of thousands of Roma people and people with mental or physical disabilities.
The Lend-Lease Act was created to allow the United States to lend or lease weapons, equipment or raw materials to any nation fighting the Axis. Eventually, 38 nations received about $50 billion in aid. Most went to Great Britain and the Soviet Union.
In 1948, the United States created the Marshall Plan to help rebuild war torn Europe. Eventually, 18 nations received $13 billion in food, machinery and other goods.
In March of 1974, Hiroo Onoda, a Japanese soldier still fighting the war, was found by a search party on the island of Lubang in the Philippines. After he is convinced the war is over by his former commanding officer, he is then flown to Manila and formally surrenders to President Ferdinand Marcos. Onoda died January 16, 2014, at the age of 91.
September 1, 1939 - Germany invades Poland. Denmark, Luxembourg, the Netherlands, Norway, Belgium and France soon fall under German control.
June 10, 1940 - Italy joins the war on the side of Germany by declaring war against Britain and France. Fighting spreads to Greece and Northern Africa.
June 14, 1940 - German troops march into Paris.
July 1940-September 1940 - Germany and Great Britain fight an air war, the Battle of Britain, along the English coastline.
September 7, 1940-May 1941 - German bombing campaign of nightly air raids over London, known as the Blitz.
June 22, 1941 - Germany invades the Soviet Union.
December 7, 1941 - Japan attacks the US Navy base at Pearl Harbor in Hawaii, destroying more than half of the fleet of aircraft, and damaging all eight battleships. Japan also attacks Clark and Iba airfields in the Philippines destroying over half of the US Army's aircraft there.
December 8, 1941 - The US declares war on Japan. Japan invades Hong Kong, Guam, the Wake Islands, Singapore and British Malaya.
December 11, 1941 - Germany and Italy declare war on the United States.
1942 - The Allies stop the Axis Powers' advance in Northern Africa and the Soviet Union.
February 1942 - Japan invades the Malay Peninsula. Singapore surrenders within a week.
June 4-6, 1942 - Japan's plans to invade the Hawaiian Islands, starting at Midway Island, but the United States cracks the code of the mission. Japan attacks Midway and loses four aircraft carriers and over 200 planes and pilots in the first clear victory for the United States.
August 19, 1942 - The battle for Stalingrad begins as Germany pushes further into Russia.
August 1942-February 1943 - US Marines fight for and hold the Pacific island of Guadalcanal.
October 23, 1942 - British troops push Axis troops into retreating to Tunisia in the Second Battle of El Alamein.
February 1, 1943 - The German troops in Stalingrad surrender, defeated in large part by the Soviet winter. The defeat marks the halt of Germany's eastbound advance.
July 10, 1943 - Allied forces land in Italy.
July 25, 1943 - The King of Italy is restored to full power, and Mussolini is deposed and arrested.
November 1943-March 1944 - US Marines invade the Solomon Islands at Bougainville to recapture it from the Japanese.
June 6, 1944 - D-Day, in which Allied forces land on five beaches at Normandy: Utah, Omaha, Gold, Juno and Sword. The landing includes over 5,000 ships, 11,000 airplanes and over 150,000 service men.
August 25, 1944 - American and Free French forces liberate Paris.
January 27, 1945 - Soviet troops liberate the Auschwitz camp complex, located near Krakow, Poland.
February 19-March 26, 1945 - US Marines battle the Japanese for the island of Iwo Jima.
April 12, 1945 - Roosevelt dies in Warm Springs, Georgia. Vice President Harry Truman takes the oath of office as president.
April 25, 1945 - Soviet troops surround Berlin.
April 28, 1945 - Mussolini is killed attempting to escape to Switzerland.
April 29, 1945 - US soldiers liberate the Dachau concentration camp outside of Munich, Germany.
April 30, 1945 - Hitler and wife Eva Braun commit suicide.
May 7, 1945 - Germany surrenders in a red school house in Reims, Germany, Eisenhower's headquarters. Victory in Europe (V-E) Day is celebrated on May 8 because that is the day the armistice went into effect.
May 8, 1945 - V-E Day. The war in Europe is officially over.
July 16, 1945 - First successful test of the atomic bomb in Alamogordo, New Mexico.
July 29, 1945 - Truman warns Japan that the country will be destroyed if it does not surrender unconditionally. Japan continues fighting.
August 6, 1945 - The first atomic bomb used in warfare, nicknamed Little Boy, is dropped on the Japanese city of Hiroshima, killing up to 140,000 people.
August 9, 1945 - After getting no response from the Japanese government after the Hiroshima bombing, a second atomic bomb, nicknamed Fat Man, is dropped on Nagasaki, killing up to 80,000 people.
August 14, 1945 - Japan unconditionally agrees to accept the terms of the Potsdam Declaration and end the war. Victory over Japan (V-J) Day is declared.
September 2, 1945 - Japan signs the formal surrender aboard the USS Missouri in Tokyo Bay.