The world war was the biggest, bloodiest and most deadly conflict in history. It cost over 65 million lives and shattered the economies of many countries. The war started because of complex relationships between European powers.

During the 19th century, many European countries signed alliances with each other – mutual defense agreements that promised to help each other militarily if they were attacked. But these arrangements were often secret from other nations. This system helped to keep the major powers constantly jockeying for position. The assassination of Austrian Archduke Franz Ferdinand by a Serbian nationalist in June 1914, set off a chain reaction. Germany invaded neutral Belgium, which was part of the Triple Entente involving France and Britain (the Allies), Russia and Austria-Hungary (the Central Powers).

As the battles began in August 1914, the alliances split into two groups – the Allies and the Central Powers. This tipped the scales toward war.

The big powers were experienced at building empires and believed they had superiority over the Pacific, Asian and African peoples they had conquered. They were convinced the fighting would be short and easy.

But as the war progressed, each side became more desperate for victory. The Allies wanted to stop Germany from gaining control of the seas and markets in Europe and the rest of the world, and the central powers feared a British takeover of their empire. This created a toxic balance of structural forces that reached a tipping point when Germany violated Belgium’s neutrality and refused to withdraw its troops.