1. System of Alliances:
A complex network of alliances had developed among European countries by the early 20th century. These alliances often involved mutual defense agreements, meaning if one country was attacked, its allies were obligated to come to its aid.
- Triple Alliance: Germany, Austria-Hungary, and Italy (although Italy remained neutral at the beginning of the war).
- Triple Entente: France, Russia, and Great Britain.
When Austria-Hungary declared war on Serbia after the assassination, Russia, as Serbia's ally, began mobilizing its army in support. Germany, in response to Russian mobilization, declared war on Russia and France, triggering the wider conflict.
2. Imperial Rivalry:
World War 1 also reflected longstanding rivalries among European powers, particularly between Britain, France, and Germany. These rivalries were fueled by competition for colonies, trade, and military dominance.
3. Nationalism and Militarism:
Growing nationalist sentiments and militarism contributed to the tensions leading up to the war. Many European countries had been engaged in an arms race, building up their military capabilities. Patriotism and a sense of national pride played a significant role in shaping public opinion and government decisions related to war.
4. Failure of Diplomacy:
Despite attempts at diplomatic mediation and negotiations between the major powers, diplomatic efforts failed to resolve the crisis that was triggered by the assassination. Tensions escalated rapidly once military mobilization began, and the situation spiraled out of control.
5. Domino Effect:
Once major powers like Germany, Russia, and France were at war, other countries felt compelled to join the conflict to protect their interests or honor alliance commitments. For instance, Japan entered the war on the side of the Allies, primarily to seize German territories in Asia.
6. Colonial Interests:
Some countries, like Italy and the Ottoman Empire, were drawn into the war due to territorial ambitions or the desire to expand their colonial holdings.
In summary, a combination of factors, including alliances, imperial rivalries, nationalism, militarism, diplomatic failures, and the domino effect, led to the outbreak of World War 1 and the involvement of other countries beyond the initial conflict between Austria-Hungary and Serbia.