On 28 June 1914, Archduke Franz Ferdinand of Austria-Hungary and his wife were assessed in Sarajevo by Bosnian Serb nationalist Gavrilo Princip. This attack was the immediate cause of the outbreak of the First World War, but the real causes lay deeper. The beginning of the 20th century was marked by a nationalist and militaristic sentiment that started an arms race. It led to tensions between the major powers in Europe and each country began to plan for a possible war.
Several alliances were forged in the run-up to the war. Germany and Austria-Hungary were allies. France had an alliance with Russia. The Germans were working on a major expansion of the fleet, which alarmed Great Britain. The British had traditionally been the ruler of the sea and Germany’s naval plans led the British to approach their old enemy France.
The assassination of Franz Ferdinand set off a chain reaction. On 23 July Austria-Hungary issued an ultimatum to Serbia. The attack had to be sorted out and the conditions laid down led to a major breach of Serbia’s sovereignty. The Serbs refused and mobilised their army. On 28 July, Austria-Hungary declared war on Serbia and was supported by Germany. The Serbs were supported by Russia and the Russians began mobilising their army on 30 July.

From the Nevers 1914 collection
Germany declared war on Russia on 1 August and because of its alliance with the Russians, France now also began to mobilise its armies. On 3 August Germany declared war on France. On their way to France, the German armies passed through neutral Belgium. The Belgians defended themselves against the German invasion and because Great Britain had guaranteed Belgium’s neutrality, the British now also became involved in the war. In one week, all major European powers were at war with each other. The war was welcomed by all. France saw it as an opportunity to take revenge for the humiliating defeat of 1870 and wanted to retake Alsace-Lorraine. A short war was expected and everyone would be home by Christmas.
The first weeks
Germany feared it would have to fight on two fronts simultaneously against both France and Russia. That is why it had already worked out the Schlieffen Plan long before the war, which was to prevent a war on two fronts.
Germany estimated that a great deal of time was needed in Russia to mobilise its army. It therefore wanted to deal with France first so that it could then go to war against the Russians. The French army had to be defeated in 42 days. The German armies would invade through the north of France, move around Paris and enclose and destroy the French armies advancing in Alsace-Lorraine.
The Schlieffen Plan had setbacks from the start. The German armies advanced through Belgium but encountered heavy resistance from the forts near Liège, which immediately delayed the ambitious planning. The Russian army also turned out to be mobilised much faster than expected and in August the Russian armies invaded East Prussia. The German army hastily moved armies from the Western Front to the Eastern Front. With a German victory over the Russians at the Battle of Tannenberg, the immediate danger had passed.
Despite setbacks, the German advance into France went well and the French armies were pushed back towards Paris. From 5 to 12 September, a huge battle took place on the River Marne. The German armies were defeated by the allied French and British armies. The Germans had to withdraw, but the Allies failed to achieve a decisive victory and drive the Germans out of France.
A stalemate ensued. Germany was now engaged in a two-front war and on the western front in Belgium and France, the armies began to dig in. This started a hopeless trench warfare. The hope that everyone would be home by Christmas was gone.
The Western Front
The Western Front ran from West Flanders in Belgium via northern France to Alsace, where the French offensive to retake Alsace-Lorraine had stalled on the peaks of the Vosges mountains. Both the German and Allied armies built an extensive system of trenches. Between the trenches of both sides lay no man’s land. Attempts to break through each other’s lines led to pointless offensives in which hardly any ground was gained. Heavy shelling and the use of the machine gun claimed many casualties. Soldiers who survived the bombings were mutilated for the rest of their lives and soldiers died a horrific death from the use of poisonous gases.

Small Atlas of the War, 1918
In 1916 the German army tried to break the deadlock. On 16 February it launched a major offensive against the city of Verdun in northern France with a devastating bombardment. The battle lasted until December and became one of the bloodiest battles in history. The French eventually managed to hold out and in December the front line was almost back in the same position as in February. During the battle, 263.000 soldiers were killed on both sides and 492.000 were wounded.
The Allies, in turn, tried to break through the German lines at the River Somme. The Battle of the Somme began on 1 July 1916 and 30.000 soldiers were killed or wounded in the first hour of the battle alone. This offensive to break the stalemate also failed. The life of the soldiers in the trenches was unbearable and hopeless. Soldiers were knee-deep in mud and the bodies of the dead often could not be buried, leading to a terrible stench and unsanitary living conditions. And so the war dragged on.
The end
The naval blockades of the British navy caused a lack of everything in Germany. A revolution broke out in Russia in 1918. The Bolsheviks came to power and sought peace with Germany. After the conclusion of peace, Germany was able to move its troops from the Eastern Front to the Western Front. In the summer of 1918, the German armies made one last attempt to win the war. The offensive was initially successful and the Germans made major gains in territory. In the end, the allied armies struggled to hold out and this breakthrough failed in the end.

Detail of a 45x107mm glass stereoview published by Brentano’s
On 6 April 1917, the United States had declared war on Germany and sided with the Allies. The supply of fresh American troops and the large shortages in Germany eventually caused Germany to capitulate. The armistice was signed on 11 November 1918, ending a conflict that had cost millions of victims worldwide.
Used source: World War I – via: en.wikipedia.org