WW1 was a war that stretched from 1914 to 1918, resulting in unprecedented destruction and unimaginable consequences. Among the hundreds of debateable causes, many reasoned that Militarism, alliances, Nationalism, Imperialism and the assassination of Archduke Ferdinand are the most important ones that led to the start of the great war. Among these five, I believe that the alliances formed between countries are the main and most important cause of World War 1.
The alliances between Germany, Austria-Hungary, Ottoman Empire and France, Britain, Russia are formed because of the increasing political tension and untrust between the countries. At the time, the alliances may have helped promote peace and cooperation in Europe, but it was also an extremely risky arrangement as it would drag in all the other countries if only two start fighting. Indeed, after the assassination of Archduke Ferdinand, what was originally a conflict between Austria-Hungary and Serbia eventually erupted into a full scale war between several countries. This proves that the alliances ultimately magnified the problems and led the countries into extreme vulnerability towards any conflict.
Considering the tension and rising conflicts that already exists between countries, these alliances only made any conflict larger and harder to solve, thus increasing the chance of a great war. For example, France and Germany have despised each other for decades since the French lost a piece of land to the Germans. The alliances furthur separated these two countries, so they also mistrusted each other, which made them eager to fight each other once the war started. The alliances divided the countries along a harsh line, creating distinct sides like a chess game. While this arrangement may provide security and trust among one's allies, it greatly antagonised their clear enemies, ultimately creating even more tension and hatred between the countries.