When the Germans got to the Belgian city of Liège, the Belgians fought very hard to stop them from coming into the city. The Germans did finally push the Belgians out of the city, but it had taken longer than the German generals had planned. Then the Germans attacked the north side of the French army. The French and the British moved men up to fight the Germans. They could do this because the Belgians had fought so long at Liège. But the Germans pushed the French back at the frontiers, and the British held the Germans back at Mons, but afterwards they also fell back to join up with the retreating French army, until they were stopped at the river Marne. This was the First Battle of the Marne or "Miracle of the Marne".
In the East, the Russians had attacked the Germans. The Russians pushed back the Germans, but then the Germans defeated the Russians at the Battle of Tannenberg.
Trench warfare killed great numbers of soldiers. New weapons, such as machine guns, and long-range artillery had an increased rate of fire that cut down huge numbers of soldiers during mass charges, a tactic leftover from older warfare. The men on both sides took spades and dug holes, because they did not want to be killed. The holes joined up into trenches, until the lines of trenches went all the way from Switzerland to the North Sea. In front of the trenches, there was barbed wire that cut anyone who tried to climb over it, and land mines that blew up anyone who tried to cross. Late in the war, poison gas was also an important weapon.
The new machine guns, artillery, trenches and mines made it very difficult to attack. The generals had fought many wars without these, so they ordered their armies to attack in the old style of marching in rows- allowing the enemy to shoot them down easily. At the Battle of the Somme in 1916 60,000 British men died in a single day. It was one of the bloodiest days in the history of the British army. Late in the war the British and French invented tanks and used them to attack entrenched Germans but could not make enough of them to make a big difference. The Germans invented special Sturmabteilung tactics to infiltrate enemy positions, but they also were too little, too late.
The British used whistles to communicate to other soldiers, so before they shelled the German trenches, they would sound the whistle. However, the Germans caught on to this tactic after a while, so after the shelling, when the British soldiers came to finish off the German soldiers, the Germans were ready with their machine guns, because they knew the British were coming.
Airplanes were first used extensively in World War I. Airplanes were not used very much in fighting before World War I. It was the first war to use airplanes as weapons. Airplanes were first used for reconnaissance, to take pictures of enemy land and to direct artillery. Generals, military leaders, were using airplanes as an important part of their attack plans at the end of the war. World War I showed that airplanes could be important war weapons.
Airplanes in World War I were made of wood and canvas, a type of rough cloth. They did not last for a long time. They could not fly very fast at the beginning of the war. They could only fly up to 116 kilometers per hour, or 72 miles per hour. At the end of the war they could fly up to . But they could not fly as fast as planes today. Guns were put on planes for the first time during the war. Pilots, people who fly the plane, used the guns to shoot enemy planes. One pilot used metal sheets, pieces of metal, to armor his airplane. Other pilots began using metal sheets, too. Pilots also made their airplanes better with machine guns, guns that shoot bullets much faster. Machine guns made fighting harder and more dangerous between airplanes.
Pilots had to wear certain clothes when flying an airplane in World War I because they flew high where the air is cold. The pilot's clothes kept them warm and protected them from the wind and cold. Pilots wore a leather coat to protect their bodies. They wore a padded helmet and goggles, large glasses with special lenses, to protect their head and face. They wore a scarf around their neck. The scarf kept the wind from blowing against their neck when they turned their head.
The German leaders decided to use submarines. These submarines were named U-boats, from the German word Unterseeboot (meaning underwater boat). The U-boats attacked passenger ships such as RMS Lusitania carrying civilians to the United Kingdom. They did not follow the laws of war, because the British would be able to easily destroy them if they did. America was selling weapons to Germany's enemies but not to Germany, thus not being neutral ("neutral" means to not take a side during a conflict). Many American and British noncombatants were killed by the submarines.
Germany also wrote a secret telegram note to Mexico in code suggesting that the two countries work together to attack the United States. This note is called the Zimmerman Telegram because it was sent by Arthur Zimmerman. It offered Mexico land in the southwestern United States that the United States took in previous wars. Spies from the United Kingdom found out about the note and told the United States. American people became angry and many decided that they wanted their country to enter the war against Germany. For the Zimmermann Telegram as well as the sinking of American ships by German U-boats, on April 6, 1917 the United States declared war against Germany and joined the Allies.
The defeat of Russia on the Eastern Front caused unrest inside the Empire.
In 1917, there was a revolution in Russia. The Tsar Nicholas II had to say he would not be Tsar any more, and that the people should have power. At first it was thought that Russia would fight harder now that the Tsar was gone. However, the Russian people did not want to fight anymore, because there was not sufficient food, appropriate armament, or adequate roads to supply its army. The war had been putting burdens on them, and many of them were poor and hungry. They began to hate their new government because it would not stop the war.
Then, there was the October Revolution. Two factions fought to rule over Russia. The Mensheviks lost against the Bolsheviks. The leader of the Bolsheviks was Vladimir Lenin (1870-1924) a Communist who followed the ideas of Karl Marx. The new government asked the Germans for peace and signed a peace treaty called Brest-Litovsk with the Central Powers in March 1918 at the city of Brest-Litovsk. The Germans and Russians stopped fighting. This gave Germany land in Eastern Europe and the Baltic Sea including the Baltics, Poland, Ukraine and Belarus. Finland also gained independence during the treaty.
After the war, the Germans had to agree to the Treaty of Versailles. Germany had to pay approximately $31.5 billion in reparations. They also had to take responsibility for the war. Part of the treaty said the countries of the world should come together to make an international organization to stop wars from happening. This organization was called the League of Nations. The United States Senate did not agree with this, even though it was the idea of the US president, Woodrow Wilson. Woodrow Wilson tried to tell the American people that they should agree, but the United States never joined the League of Nations. Problems with the Treaty in Germany would later lead to the World War II.
World War II