Additionally, these countries began to build up their military. Another similarity of World War I and World War II is the role the United States played in each war.
The United States didn’t join either war when they first started.
In World War I, we joined the war after Germany resumed its policy of sinking our merchant ships without warning.
In World War II, we joined the war after Japan attacked us at Pearl Harbor. A finally similarity is that in both World War I and World War II we were more sympathetic to the Allies than to the Central Powers and Axis Powers.
Second, both wars were "total wars" that were won by the side that could manufacture the most weapons.
Finally, both were wars that ended with victories for the countries that had dominated the world order before the war.
Different pacts and alliances made certain that if two countries were to go to war, a bunch of other countries must join in (making it a world war as opposed to a war between two countries) and an increase in weapons from the industrial revolution made militarism a serious threat.
In WWII, German nationalism was rising after its defeat and humiliation in the wake of the Treaty of Versailles.
In WWI, tensions rose between European nations over imperial territories in Africa and elsewhere in the world.
The idea of nationalism, pride or love for one's country, propelled Europeans to search for more land in order to honor their country.