What event led to world war 1
- What event triggered world war 1
- What event sparked world war 1
- What major event led to world war 1
- What event in sarajevo lead to world war 1
- What event led to the start of world war 1
- What event led to the outbreak of world war 1
- What event led to the beginning of world war 1
- What event led to the us entering world war 1
- What event led to us entry into world war 1
- What event led to the us joining world war 1
- What event led to the united states entering world war 1
- What event led to the united states entering world war 11
- What event led to the immediate outbreak of world war 1
- What event led to the united states joining world war 1
- What single event led to the outbreak of world war 1