World War I was sparked by the assassination of Archduke Franz Ferdinand, leading to the mobilization of Austria and Serbia. The Germans joined the Austrians to form the Central powers; the French, British, and Russians formed the Allied powers. Following the Battle of the Marne and the outflanking attempt of both nations in the "Race to the Sea", trench warfare ensued, leaving the war in a great deadlock.
Major operations by the Germans at the Battle of Verdun and by the British and the French at the Battle of the Somme were carried out, and new technology like tanks and chlorine gas were used. Following the USA's and the USSR's entrance into the war, the Germans and their allies were eventually defeated.
World War II ensued after Germany's invasion of Poland, forcing Britain and France to declare war. Germany quickly defeated France and Belgium, later aided by Italy. A hasty evacuation occurred at Dunkirk to save the Allied army from complete destruction. The Germans then attacked USSR and marched to take over the Soviet resources, but were thwarted.