World War I was the culmination of events set in motion decades before that fateful day in 1914. Germany had been planning a war since the mid 1870's and military leaders were determined to have it. Europe had enjoyed a century of peace until an assassin's bullet crushed any hope of maintaining that peace. While the immediate cause for the start of WWI was the assignation of Archduke Francis Ferdinand, conflict on continental Europe was inevitable.
After the Napoleonic wars came to an end Great Britain, Austria, Prussia, and Russia declared their intent to establish " a firm peace, based on a just equilibrium of strength among the powers." A balance of power was created, and it successfully kept European nations in check. The collapse of the balance of power system, brought on mainly by German Alliances and desire to dominate Europe, forced nations such as France, England, and Russia to form their own alliance in the event of an attack by Germany. The Triple Alliance, Germany, Austria-Hungary, and Italy were heading for a showdown with the Triple Entente of England, France, and Russia.
As it became apparent that war was on the horizon various countries tried to avoid an escalation in tensions, but no matter how hard they tried German and Austrian military leaders were not about to let their country live and let live. The road to war was quickly approaching; neither side knew what they were about to embark on. The combatants on both sides foolishly were convinced any conflict would be short and glorious. They believed domestic economies and the network of international commerce and finance could not withstand more than a few months of disruption. Both sides were sadly mistaken.
Over the next four years Europe was engulfed in a war that was neither brief nor glorious. In the end, both sides were unprepared to deal with the realities of modern industrialized warfare. Once fighting started Italy backed out of its pact with Germany and Austria, and with the help of the United States the Triple Entente defeated the Dual Alliance.