Photos: World War II in pictures German troops march through occupied Warsaw, Poland, after invading the nation on September 1, 1939, and igniting World War II. Hide Caption 1 of 38

Photos: World War II in pictures German Chancellor Adolf Hitler speaks to Nazi party officials in 1939, the year of the German blitzkrieg into Poland. Denmark, Luxembourg, the Netherlands, Norway and Belgium soon fell under German control. When France came under occupation less than a year later, Britain was the only remaining Western European nation fighting the Third Reich, and the United States had not yet entered the war. Hide Caption 2 of 38

Photos: World War II in pictures In Asia, Japanese troops occupy a strategic point on Chusan Island on July 14,1939, during the Sino-Japanese War. Japan signed the Tripartite Pact in 1940, formally allying with Germany and Italy, and by 1942 most of the Asian Pacific Rim had come under its domination. Hide Caption 3 of 38

Photos: World War II in pictures German soldiers on the Esplanade du Trocadero view the Eiffel Tower. In June 1940, German troops marched into Paris, forcing France to capitulate and establish the pro-Axis Vichy French government. Hide Caption 4 of 38

Photos: World War II in pictures British Hawker Hurricanes fly in formation during the Battle of Britain in 1940. The planes were a first line of defense against German bombers attacking England. The battle, fought between July 10 and October 31, 1940, was the first major battle to be won in the air. The Royal Air Force's victory thwarted Hitler's plans for invading Britain. Hide Caption 5 of 38

Photos: World War II in pictures Smoke rises behind Tower Bridge during the first mass daylight bombing of London on September 7, 1940. Hide Caption 6 of 38

Photos: World War II in pictures Italian dictator Benito Mussolini, left, with Hitler, center, and other leading Nazis, visits Germany during the war. Italy and Germany formed an alliance before the outbreak of war, but Italy remained a non-belligerent until June 10, 1940, when it declared war on Britain and France. Fighting spread to Greece and North Africa. Hide Caption 7 of 38

Photos: World War II in pictures German tanks and infantry attack Soviet positions on the Eastern Front. On June 22, 1941, Germany broke its Non-Aggression Pact with the Soviet Union, launching the bloodiest theater of the war. Though the estimates vary greatly, Russia suffered the most war casualties of any nation in World War II -- as many as 13.8 million military deaths. Estimates of civilian deaths from military action, crimes against humanity, starvation and disease are as high as 9 million. Hide Caption 8 of 38

Photos: World War II in pictures A view of U.S. ships in Pearl Harbor, Hawaii, after the Japanese attack on December 7, 1941. The USS West Virginia and USS Tennessee are in the foreground. The attack destroyed more than half the fleet of aircraft and damaged or destroyed eight battleships. Japan also attacked Clark and Iba airfields in the Philippines, destroying more than half the U.S. Army's aircraft there. Hide Caption 9 of 38

Photos: World War II in pictures U.S. President Franklin D. Roosevelt signs the declaration of war against Japan on December 8, 1941. Italy and Germany immediately declared war on the United States, and on December 11, Roosevelt signed the U.S. declarations of war against those nations. Hide Caption 10 of 38

Photos: World War II in pictures British prisoners of war leave Hong Kong for a Japanese prison camp in December 1941. Hide Caption 11 of 38

Photos: World War II in pictures Anti-aircraft fire glows over Algiers during a night raid on November 23, 1942. In 1942, the Allies stopped the Axis advance in North Africa and the Soviet Union. Hide Caption 12 of 38

Photos: World War II in pictures Black smoke rises from demolished buildings after Japanese air forces attacked the U.S. Navy base on Midway Atoll during the Battle of Midway in June 1942. The four-day battle became a major victory for the U.S. Navy, which sunk four Japanese aircraft carriers, and it marked a turning point in the war in the Pacific. Hide Caption 13 of 38

Photos: World War II in pictures Balloon operators from Britain's Women's Auxiliary Air Force, or WAAF, report for inspection in a hangar used to store balloons, at a facility in the UK. During World War II, women played a significant role in the war effort. They took jobs in "defense plants and volunteered for war-related organizations, in addition to managing their households," according to the World War II museum in New Orleans. Hide Caption 14 of 38

Photos: World War II in pictures British troops land near Algiers, Algeria, during Operation Torch in November 1942. Operation Torch was the British-American invasion of Vichy-held French North Africa, and marked the first major action by the Western allies against the German army. Hide Caption 15 of 38

Photos: World War II in pictures Soviet soldiers advance against the German army during the Battle of Stalingrad. The battle for the city on the Volga River (present-day Volgograd) was a major defeat for Germany and a turning point in the war. The battle lasted more than five months, ending in February 1943, at the cost of at least 160,000 German soldiers killed or captured. However, even conservative estimates of Russian casualties are much higher. Hide Caption 16 of 38

Photos: World War II in pictures German prisoners captured at the beachhead of Anzio, Italy, leave a landing craft on their way to a prison camp in 1944. The amphibious landing and ensuing battle helped Allied forces break a months-long stalemate south of Rome and ultimately defeat the Germans in Italy. Hide Caption 17 of 38

Photos: World War II in pictures French refugees live in a quarry near Fleury sur Orne. During the bombing in that area, 20,000 refugees lived in the quarries. Hide Caption 18 of 38

Photos: World War II in pictures U.S. troops assault Omaha Beach during the invasion of Normandy on June 6, 1944. On D-Day, Allied forces landed on five beaches -- Utah, Omaha, Juno, Gold and Sword -- taking the first step in establishing the Western Front in Europe. The landing included more than 5,000 ships, 11,000 airplanes and 150,000 soldiers. More than 35,000 Allied troops were killed during the Normandy Campaign, which lasted till the end of August 1944. Hide Caption 19 of 38

Photos: World War II in pictures A crowd gathers to cheer Gen. Charles de Gaulle at the Place de la Concorde on August 26, 1944, a day after the liberation of Paris. Hide Caption 20 of 38

Photos: World War II in pictures Soldiers of an infantry division move into the mist over a snow-covered field near Krinkelter, Belgium, on December 20, 1944, during the Battle of the Bulge, a surprise German counter-offensive against Allied forces as they closed in on German soil from the west. It resulted in more combined U.S. losses (nearly 90,000 killed, wounded or captured) than any battle of the war. Hide Caption 21 of 38

Photos: World War II in pictures U.S. Marines of the 28th Regiment, 5th Division, raise the American flag atop Mount Suribachi, Iwo Jima, on February 23, 1945. Strategically located only 660 miles from Tokyo, the Pacific island was essential to launching land-based bombers against Japan. It was the bloodiest battle in the history of the U.S. Marine Corps, which suffered more than 27,000 casualties. Of some 18,000 Japanese soldiers defending the island, 216 survived. Hide Caption 22 of 38

Photos: World War II in pictures German prisoners captured at Friedrichsfeld march through a town in Germany after the crossing of the Rhine River by the U.S. 9th Army on March 26, 1945. Hide Caption 23 of 38

Photos: World War II in pictures From left, British Prime Minister Winston Churchill, U.S. President Franklin D. Roosevelt and Russian Premier Joseph Stalin at the Yalta Conference on February 1945. Hide Caption 24 of 38

Photos: World War II in pictures Prisoners line block 61 of Buchenwald concentration camp in April 1945. The construction of Buchenwald started July 15, 1937, and the camp was liberated by U.S. Gen. George Patton's troops on April 11, 1945. Between 239,000 and 250,000 people were imprisoned in the camp. About 56,000 died, including 11,000 Jews. Hide Caption 25 of 38

Photos: World War II in pictures President Franklin D. Roosevelt's funeral procession goes down Connecticut Avenue on its way to the White House. Roosevelt died on April 12, 1945, in Warm Springs, Georgia, just weeks before Germany's surrender. Hide Caption 26 of 38

Photos: World War II in pictures Harry S. Truman takes the oath of office on April 12, 1945, as he becomes the 33rd president of the United States. Standing beside him are his wife, Bess, and daughter Margaret. Hide Caption 27 of 38

Photos: World War II in pictures The bodies of Benito Mussolini, left, and his mistress, Clara Petacci, second from left, hang from the roof of a gasoline station after they were shot by anti-Fascist forces while attempting to escape to Switzerland on April 28, 1945. Hide Caption 28 of 38

Photos: World War II in pictures Russian soldiers wave their flag, made from tablecloths, over the ruins of the Reichstag in Berlin on April 30, 1945. That day, as the Soviets were within blocks of his bunker at the Reich Chancellery, Adolf Hitler committed suicide. Hide Caption 29 of 38

Photos: World War II in pictures British Prime Minister Winston Churchill addresses the celebrating crowds from the balcony of the Ministry of Health in Whitehall, London, on V-E Day, May 8, 1945. The war in Europe was officially over. Hide Caption 30 of 38

Photos: World War II in pictures Soldiers rush an injured U.S. Marine from a battlefield during the Battle of Okinawa in June 1945. The battle, the bloodiest of the war in the Pacific, raged for nearly three months and heightened U.S. concerns for the enormous casualties that could be anticipated in the planned invasion of Japan's main islands. Hide Caption 31 of 38

Photos: World War II in pictures A photograph on display at the Bradbury Science Museum shows the first instant of the first atomic bomb test, on July 16, 1945, at 5:29 a.m. at Trinity Site in New Mexico. The Potsdam Declaration, announced 10 days later, called for Japan's unconditional surrender, threatening "prompt and utter destruction." It did not, however, specifically mention the bomb. Hide Caption 32 of 38

Photos: World War II in pictures Col. Paul W. Tibbets Jr., center, stands with the ground crew of the B-29 bomber "Enola Gay," which Tibbets piloted on August 6, 1945. The atomic bomb dropped on Hiroshima, Japan, that day killed an estimated 130,000 people. Hide Caption 33 of 38

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Photos: World War II in pictures A patient suffering severe radiation burns lies in the Hiroshima Red Cross hospital in August 1945. Many of those who survived the initial blast on August 6 died of severe radiation-related injuries and illnesses. Hide Caption 35 of 38

Photos: World War II in pictures A dense column of smoke rises more than 60,000 feet into the air over Nagasaki, the result of an atomic bomb dropped on August 9, 1945. An estimated 60,000 to 70,000 were killed in the Nagasaki blast. Six days later, a little after noon local time on August 15, Emperor Hirohito's announcement that Japan had accepted the terms of the Potsdam Declaration was broadcast on radio. Japan had surrendered. Hide Caption 36 of 38

Photos: World War II in pictures A jubilant American sailor kisses a nurse in New York's Times Square on August 14, 1945, as he celebrates the news that Japan has surrendered. (Because of the time difference between the two nations, the surrender occurred August 15 in Japan). Hide Caption 37 of 38