The four trends that pushed Europe toward war in the late 1800s and early 1900s were:
1- The alliance system
2- Militarism: which means that either the government or the people or both desired to keep a very strong military capability. This military capability was then used aggressively to spread the country's interest and promote them.
3- Nationalism: which means that there was a group of different systems (political, economic and social) working on promoting interests of a particular nation in order to gain self-governance, or full sovereignty, over the group's homeland.
4- Imperialism: which means that the country actually expanded its power by the acquisition of territories