In World War 1 the assassination of Archduke Franz of Austria-Hungary was the cause. But the main causes of it were, MAIN (Militarism, Alliances, Imperialism, and Nationalism). Militarism was a “Arm’s race” which fell on civilian populations with the form of taxes which were high. Between the years 1870-1914, all of the major powers except Great Britain and the United States. British had a large Navy so Germany wanted a large Navy too and Germany and France both competed to get larger Navies. Alliances was the thought that would promote peace.The Alliance system primarily came about because after 1870 Germany set a precedent to maintain a balance of power within Europe. Imperialism also pushed the countries towards adopting alliances. Imperialism also brought nations who didn't want to compete, get into conflicts, and or have any agreements. Nationalism was also a new and powerful source of tension in Europe and it created new areas of interest over which nations could compete. After the assassination, Austria declared war on Serbia. A few days later, Germany declared war on Russia, then on France. Germany tried to beat Britain by bombing their cities (Mostly Londo). Germany wanted to destroy British people's economy. They didn't succeed and so there were many fights between the planes and the groups.
World War 1 was fought between major alliances of countries which were the Central Powers and the Allied Powers. Allied Powers were largely formed as a defense against the aggression of Germany and the Central Powers.Allied Powers of World War 1 involved the countries Germany, Austria, Hungary, and Turkey. They were the countries that opposed the Central Powers. Italy initially had a treaty with Germany, but secretly allied with the Allied Powers. The United States was never an official member of the allies but called itself an Associated Power. The two allied countries with the most soldiers killed were Russia with 1800000 and France with 1400000. Other countries that were or have been allied by treaty to one or more of those powers were also called Allies (Portugal and Japan by treaty with Britain).