World War I began on July 28, 1914 when Austria-Hungary declared war on Serbia after the assassination of the heir to the throne of Austria-Hungary. World War II began on September 3, 1939 when Britain and France declared war on Germany after they had invaded Poland on September 1, 1939. Both of the wars involved alliances between different groups of countries. World War I included the Central Powers which were Germany, Austria-Hungary, and Turkey. They fought against the Allied Powers which included France, Britain, Russia, Italy, Japan, and finally United States joined in 1917. World War II included the Axis Powers which were Germany, Italy and Japan against the Allied Power which were France, Britain, United States, Soviet Union and …show more content…
During World War I, the opposing armies faced each other across deep trenches along the front lines, they were protected by flying bullets and artillery shells. The German U-boat or submarine was the serious weapon of war. Poison gas, was first used by Germans and the armored tank was invented by the British. In 1943, Navajo soldiers developed a military code used for communication for the United States. During World War II, the United States developed the atomic bomb, which was first used in August of 1945. World War II, was the first major war in which bombers played a large part. The number of casualties were so much greater in World War II than in World War I. The number of casualties went from an estimated 8.5 million in World War I to over 60 million casualties in World War II. These deaths included civilian and military deaths. World War II was the first war that women served in the military. While World War I, was a global war centered in Europe, World War II fighting took place on every continent except the Antarctic and South America, and involved 61 countries. Not only were there millions of lives lost, nations were destroyed and cities were