WHAT CAUSES WORLD WAR 1

The Great Powers of Europe are divided into two rival alliances: The Triple Entente: France, Britain and Russia, united by fear and suspicion of Germany, Europe's new strongest power. And the Triple Alliance: Germany, which fears encirclement by its rivals; Austro-Hungary, clinging onto a fragile empire; and Italy, seeking gains at French expense. The spark comes on the June, in the city of Sarajevo. Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, is assassinated by a year-old Slav nationalist named Gavrilo Princip. Austro-Hungary accuses its Balkan rival Serbia of having aided the assassin, and sends an ultimatum, demanding humiliating concessions. Serbia rejects the ultimatum, and Austro-Hungary declares war. Within hours Austrian forces are shelling Belgrade. The Russian Tsar, Nicholas II, feels honour-bound to defend Serbia, a fellow Slav nation, and orders the Russian army to mobilise. German Emperor Wilhelm II has promised his support to Austro-Hungary. He and his generals see conflict with Russia as inevitable – and the sooner the better, as Russian strength grows year on year. Russian mobilisation is used to justify German mobilisation, followed by a declaration of war on Russia. Germany knows war with Russia means war with Russia's ally, France. It has developed the Schlieffen Plan to meet this threat of a war on two fronts – first, its armies will advance rapidly through neutral Belgium to encircle and destroy French armies near Paris, and win a quick victory. Then its forces can move east to deal with Russia, whose huge army will take much longer to mobilise. And so Germany declares war on France. Six million men are now marching to war across Europe. Italy, however, remains neutral. The terms of the Triple Alliance don't bind it to join an offensive war. The United States also declares its neutrality. President Wilson and the American public have no desire to get entangled in Europe's war. Britain is France's ally, but at first it's not clear if it will join the war against Germany. But when German troops invade Belgium, whose neutrality Britain has guaranteed, an ultimatum is sent from London to Berlin demanding they withdraw. It's ignored, and Britain declares war. A British Expeditionary Force lands in France, while the German invasion is held up for crucial days by Belgian resistance at the fortress-city of Liège. German troops commit several massacres against Belgian civilians. The atrocities are inflated by Allied propaganda, and help turn public opinion in neutral countries against Germany. France, unaware of Germany's great encircling attack, launches Plan XVII, an offensive into German territory. But in the Battle of the Frontiers they're driven back, with enormous losses on both sides. The British Expeditionary Force clashes with the German army at Mons. But the British are heavily outnumbered, and soon join the French in retreat. The Allies make their stand at the River Marne, miles outside Paris. Their desperate counterattack saves the city and drives the Germans back. Both sides suffer a quarter of a million casualties. 'The Race to the Sea' begins, as both sides try to outflank each other to the north. A series of clashes leads to the First Battle of Ypres, where the Allies desperately cling on and prevent a German break through. There are more heavy losses on both sides. The two armies then dig-in along the entire -mile front, seeking shelter from deadly machinegun fire and artillery shells. Trench warfare has begun. British warships win the first naval battle of the war at Heligoland Bight, sinking three German cruisers. Britain has the most powerful navy in the world: modern battleships to Germany's They now impose a naval blockade on Germany, preventing contraband goods, including food, from reaching it by sea. The aim is to bring Germany's economy to its knees and force it to surrender. But a week later, the British cruiser HMS Pathfinder becomes the first victim in history of a lethal new weapon - the submarine-launched torpedo. German submarines, or U-boats, have a surface range of miles, and can attack undetected from beneath the waves. They herald a deadly new challenge to Britain's command of the seas. On the Eastern Front, Russian armies invade East Prussia. But they blunder into disaster at the Battle of Tannenberg, where General von Hindenburg and his Chief of Staff Erich Ludendorff mastermind a brilliant German victory, taking prisoners and destroying an entire Russian army. The Russians contribute to their own defeat by transmitting uncoded wireless messages. A second massive German victory at Masurian Lakes forces the Russians into retreat. In just six weeks, the Russian army suffers nearly a third of a million casualties. Meanwhile Austro-Hungary's invasion of Serbia suffers a humiliating reverse at the Battle of Cer. Austro-Hungary's offensive against Russia also ends in disaster and retreat, with the loss of more than men. The fortress-town of Przemyśl is cut-off and besieged by the Russians. The Germans are forced to come to the rescue, launching a diversionary attack towards Warsaw. It leads to weeks of brutal, winter fighting around the Polish city of Łódź, but there is no clear winner. Meanwhile, the Turkish Ottoman Empire has joined the Central Powers, declaring war on its old enemy, Russia. Turkish warships bombard the Russian ports of Odessa and Sevastopol, while in the Caucasus, Russian troops cross the Turkish frontier. Beyond Europe, the war rages on the world's oceans and in far-flung European colonies. German troops cross into British East Africa (modern Kenya) and occupy Taveta; while Allied forces seize the German colony of Togoland (modern Togo). But British forces invading German Cameroon are defeated at Garua and Nsanakong... while a strong force attacking German South-West Africa, modern Namibia, is captured at Sandfontein. A month later, British landings at Tanga end in chaos and defeat at the hands of a much smaller German force led by Colonel von Lettow-Vorbeck. Cut-off from Germany, Lettow-Vorbeck goes on to wage a highly successful guerilla war against the Allies, tying down huge numbers of troops. In Asia, Japan honours its treaty with Britain and declares war on Germany. Japanese forces go on to seize the German naval base at Tsingtao. The German colonies of Samoa and New Guinea surrender to troops from New Zealand and Australia.