The four long-term causes of World War I are often summarized by the acronym M.A.I.N.:

1. Militarism: A build-up of military forces and a focus on military power. This led to an arms race between European powers, increasing tensions and making conflict more likely.  
2. Alliances: The formation of complex alliances between European nations meant that a conflict between two countries could quickly escalate into a larger war.  
3. Imperialism: Competition for colonies and resources fueled tensions between European powers.  
4. Nationalism: Intense nationalistic feelings, especially in the Balkans, contributed to instability and conflict.  

These factors combined to create a volatile situation in Europe, and the assassination of Archduke Franz Ferdinand of Austria-Hungary in 1914 served as the spark that ignited the global conflict