The impact of the First World War is still with us. In many respects the events of modern Europe are a direct result of what happened during World War I. Adolph Hitler himself was a product of the First World War. World War I also gave Russian communists opportunity to overthrow the government in Russia and proclaim communism. The events that took place in "No Mans Land" definetly had an impact on the wars to come.
The First World War had many causes. The spark of the Great War was the assassination of the Archduke Franz Ferdinand, soon to be at the throne of Austria-Hungary, and his wife by a Serbian nationalist, while traveling through Sarajevo. The Archduke was chosen as a target because Serbians feared that after he was at the throne, he would continue the persecution of Serbs living within the Austria-Hungary Empire. The Serbian terrorist organization, the Black Hand, had to carry out the assassination.
The Arms Race is the second cause. Britain at that time was the largest empire in the world, and it also had the largest navy. The navy was so big and strong because the British needed to protect their empire and maintain the sea routes between the different colonies. Kaiser William of Germany hated and envied Britain for having a stronger navy than his. He increased the German navy and built many warships. Britain responded with building more ships and increasing its navy too. This started a race for building more and better warships and it created tension and competition between those two countries.
The system of alliance were another major cause of the War. There was a feud between France and Germany about controlling the colonies, which leads to a greater conflict, the Great War. Europe at that time was divided into two rival alliance systems: Triple Entente that included Great Britain, France, and Russia and the Triple Alliance, which included the Central Powers of Austria - Hungary, Germany, and eventually the Turkish Empire. In order to balance the power, France and Russia signed an alliance. Russia saw itself as the 'protector of Slavs' in the war, and immediately mobilized. When the war began, the German decision that if they were going to have to fight Russia and France, they would strike at France first according to the Schlieffen Plan, and then turn West to Russia. Germans believed that Russia at the time was unprepared for war, and that it will take a long time for Russia to mobilize its army. So, on July 28, 1914, Austria declared war against Serbia. Russia responded by partially mobilizing against Austria as a 'protector of Slavs', and Germany insisted that Russia immediately demobilize. Russia refused to do so, and so declared war on Russia and France. When war was declared in August people involved on all sides felt that it would be a short war, and will be over by Christmas. In order for Germany to accomplish its Schlieffen Plan, Germany occupied Belgium. By August most of Belgium was under German occupation and the Schlieffen Plan appeared to be going well, but it brought Britain into the war because they had made a treaty with Belgium before, and Schlieffen Plan involved the invasion of Belgium.
One of the other major causes during the War was new weapons. In other words military commanders were not quite ready to the war with it's modern weapons and new technologies such as machine guns, also the men built trenches that ran 500 miles. The First World War was the first war to use poison gas as a military weapon. Germans also had the first submarines and used them to blockade Britain by sinking British ships. The sinking of Lusitania is the famous example of sub-warfare during World War I. The Lucitania had civilians on board, where 100 passengers were American citizens. After sinking Lusitania a letter was sent to the German Government by President Wilson to warn the German government against killing Americans citizens. The total war started when Germans used their first gas attack. Gassing was the start of total war, because it broke all limits of other wars.