Final answer:
The main causes of the First World War were the alliance system, imperialism, and nationalism.
Step-by-step explanation:
The main causes of the First World War were:
- Alliance System: The complex web of alliances between countries created a rigid system of commitments which led to the escalation of the conflict.
- Imperialism: The competition between European powers for colonies and resources led to tensions and rivalries.
- Nationalism: The intense pride and loyalty to one's own country fueled rivalries and a desire for dominance.
The combination of these factors, along with other tensions and events, ultimately led to the outbreak of the war in 1914.
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