To think about this, we should distinguish between root causes and proximate causes. The root causes are general things that pushed the US towards wanting some sort of war like the Spanish-American War. They include:
- The desire for more power. Many Americans at this point wanted the US to become a bigger and more important player on the world stage. They felt that war and an empire would be good ways to accomplish this.
- The desire for the US to prove itself. People like Theodore Roosevelt believed the US needed a war to allow it to prove its power. They felt that American men needed that sort of a challenge and an opportunity to prove their bravery and masculinity.
Then there are proximate causes that are directly connected to this war in particular. They include:
- Hatred of European colonial powers. This led Americans to support Cuba’s bid for independence.
- Yellow journalism. This stirred up American public opinion against Spain.
- The De Lome letter. This insulted America’s pride and caused a desire for revenge.
- The Maine. The explosion of this ship led most Americans to believe that Spain had blown it up. This increased their desire for revenge.