Austria-Hungary declared war on Serbia on July 28, 1914, marking the official start of World War I.

The Treaty of Versailles was signed on June 28, 1919, between the Allied Powers and Germany, officially ending World War I.

Germany invaded Poland on September 1, 1939, marking the beginning of World War II.

Operation Pearl Harbor was the name given to the surprise attack on Pearl Harbor by the Imperial Japanese Navy on December 7, 1941.

The Battle of Stalingrad, which lasted from July 1942 to February 1943, is widely regarded as the turning point of World War II in Europe.

Little Boy was the name of the atomic bomb dropped on Hiroshima on August 6, 1945.

Italy surrendered to the Allied forces on September 8, 1943, becoming the first Axis power to surrender in World War II.

The Yalta Conference was held in February 1945 between the leaders of the United States, the United Kingdom, and the Soviet Union to discuss the postwar world order.

Japan surrendered to the Allied forces on September 2, 1945, marking the official end of World War II.

The total number of casualties in World War I is estimated to be around 20 million.

The total number of casualties in World War II is estimated to be around 60 million.

Russia suffered the most casualties in World War I, with an estimated 1.7 million military deaths and 2.5 million civilian deaths.

The Soviet Union suffered the most casualties in World War II, with an estimated 27 million military deaths and 18 million civilian deaths.

Dwight D. Eisenhower was the commander-in-chief of the Allied forces in Europe during World War II.

Hideki Tojo was the commander-in-chief of the Japanese Imperial Army during World War II.