What Caused the First World War to break out?Which factor in your opinion was the most important?

As soon as war broke out in 1914, historians began to ask why and how it could possibly have happened. What had gone wrong? As the fighting spread and casualties mounted, the question became more urgent. To this day no one has come up with a definitive explanation. In the following text I will attempt to highlight the principle factors which contributed to the outbreak of the First World War. After studying these causes I shall then decide in my opinion which is the most significant factor.

The First World War broke out against a background of rivalry between the world’s greatest powers. These powers were, Britain, Germany, France, Russia and the USA and to a lesser degree, Austria-Hungry, Italy, the Ottoman Empire and Japan. No single power was dominant. The US, for example, had the strongest economy. Britain the most powerful navy, and Germany the most effective army. From 1870 onwards, the powers formed alliances for greater security. The Triple Entente consisted of France, Bri...