Answer:
I think it would be Imperialism or Alliances.
Explanation:
Alliances are glorifying military power and keeping a large army prepared for war. They also led to the Great War because each country wanted to have the largest, and most powerful empires. They also wished to have the largest fields which fought for them in the war.
Imperialism lead to the Great war because each country thought they were the best and had more of a chance and wanted to prove it to everyone.
I am still debating if it would be Nationalism too, not sure, but I hope this helps!