Europe: The Physical Setting 
While peace and harmony characterized much of Europe at the beginning of the 1900s, there were less visible-and darker-forces at work as well. One such force was the growth of nationalism. By the turn of the 20th century, a fierce rivalry had developed among Europe's Great Powers-Germany, Austria- Hungary, Great Britain, Russia, Italy, and France. This rivalry stemmed from several sources, including competition for materials and markets, territorial disputes, and mistrust born of imperialism. Added to these factors was the rise of a dangerous European arms race. The nations of Europe believed that to be truly great, they needed to have a powerful military that could quickly mobilize for war. The policy of glorifying military power and keeping an army prepared for war was known as militarism. 
Growing rivalries and mutual mistrust had led to the creation of several military alliances among the Great Powers as early as the 1870s. By 1907, two rival camps existed in Europe. On one side was the Triple Alliance-Germany, Austria-Hungary, and Italy. 0n the other side was the Triple Entente-Great Britain, France, and Russia. A dispute between two rival powers could draw all the nations of Europe into war. 
Crisis in the Balkans 
Nowhere was that dispute more likely to occur than on the Balkan Peninsula. With along history of nationalist uprisings and ethnic clashes, the Balkans was known as the "powder keg" of Europe. The situation between Serbia, which had broken away from the Ottoman Empire, and its neighbor to the north, Austria-Hungary, was particularly tense. In 1908, Austria had annexed Bosnia and Herzegovina-- two Balkan areas that the Serbians sought to rule. The Serbs were outraged and vowed to take Bosnia and Herzegovina away from Austria. Austria-Hungary responded by vowing to crush any Serbian attempt to under-mine its authority in the Balkans. 
Into this poisoned atmosphere stepped the heir to the Austro-Hungarian throne, Archduke Franz Ferdinand, and his wife, Sophie.  On June 28, 1914, the couple paid a state visit to Bosnia's capital, Sarajevo. The royal pair was shot at point-blank range as they rode through the streets of Sarajevo in an open car. The killer was Gavrilo Princip, a 19-year-old Serbian and member of the Black Hand, a secret society committed to ridding Bosnia of Austrian rule. 

Because the assassin was a Serbian, Austria decided to use the murders as an excuse to punish Serbia. On July 28, Austria declared war on Serbia. That same day, Russia, an ally of Serbia, ordered the mobilization of troops toward the Austrian border. Leaders all over Europe suddenly took notice. 
Europe Plunges into War 
Expecting Germany to join Austria, Russia also mobilized along the German border. On August 1, the German government responded by declaring war on Russia. Russia looked to its ally France for help. Not waiting for France to react, Germany declared war on France. Soon afterward, Great Britain declared war on Germany. Much of Europe was now locked in battle. 
By mid-August 1914, the battle lines were clearly drawn. On one side were. Germany and Austria-Hungary, known as the Central Powers because of their location in the heart of Europe. Bulgaria and the Ottoman Empire would later join the Central Powers in the hopes of regaining lost territories. 
On the other side were Great Britain, France, and Russia. Together, they were known as the Allied Powers or the Allies. Japan joined the Allies within weeks. Italy, which had been a member of the Triple Alliance with Germany and Austria-Hungary, later joined the Allies after accusing their former partners of unjustly starting the war. The Armenians also sided with the Allies, for which they paid a heavy price. The Ottoman Turks responded by deporting nearly 2 million Armenians. Along the way, more than 600,000 died of starvation or were killed by Turkish soldiers. 
The War Fronts In the late summer of 1914, millions of soldiers marched happily off to battle, convinced that the war would be short. As the summer of 1914 turned to fall, the war turned into a long and bloody stalemate, or deadlock, along the battlefields of France. This deadlocked region in northern France became known as the Western Front. By early 1915, opposing armies on the Western Front had dug miles of parallel trenches to protect themselves from enemy fire. This set the stage for what became known as trench warfare. In this type of warfare, soldiers fought each other from trenches. Armies traded huge losses of human, life for pitifully small land gains. 
Military strategists were at a loss. New tools of war- machine guns, poison gas, armored tanks, larger artillery, airplanes- had not delivered the fast- moving war they had expected. All this new technology did was kill greater numbers of people more effectively. 
Even as the war on the Western Front claimed thousands of lives, both sides were sending millions more men to fight on the Eastern Front.  This area was a stretch of battlefield along the German and Russian border. Here, Russians and Serbs battled Germans and Austro-Hungarians. The war in the east was a more mobile war than that in the west. Here too, however, slaughter and stalemate 
were common. 
 As the war raged on, fighting spread beyond Europe to Africa, as well as to Southwest and Southeast Asia. The Gallipoli campaign in 1915-an Allied attempt to capture the Dardanelles strait as a step toward taking the Ottoman capital, Constantinople, ended in an Allied defeat. The Allies had better luck in their assaults against German colonial possessions in Asia and Africa. Japan quickly overran German outposts in China and captured Germany's Pacific island colonies. The English and French seized control of three of Germany's four African possessions. Elsewhere in Asia and Africa, the British and French recruited subjects in their colonies for the struggle. India, South Africa, Senegal, 
Egypt, Algeria, and Indochina provided fighting troops and laborers.
 In 1917, the focus of the war shifted to the high seas. In January 1917, the Germans announced that their submarines would sink without warning any ship in the waters around Britain-a policy known as unrestricted submarine warfare.  Ignoring warnings by President Woodrow Wilson, German U-boats sank three American ships. 
Then, in February 1917, officials intercepted a telegram written by Germany's foreign secretary, Arthur Zimmermann, stating that Germany would help Mexico “reconquer” the land it had lost to the United States if Mexico would ally itself with Germany. The Zimmermann note simply proved to be the last straw. On April 2, 1917, President Wilson asked Congress to declare war on Germany. The United States entered the war on the side of the Allies. 
The Home Front World War I soon became a total war. This meant that countries devoted all their resources to the war effort. In Britain, Germany, Austria, Russia, and France, the wartime government took control of the economy. Governments told factories what to produce and how much. Numerous facilities were converted to munitions factories. Nearly every able-bodied civilian was put to work. Unemployment in many European countries all but disappeared. So many goods were in short supply that governments turned to rationing. Under this system, people could buy only small amounts of those items that were also needed for the war effort. 
Governments also suppressed antiwar activity, sometimes forcibly. In addition, they censored news about the war, fearing that honest reporting of the war would turn people against it. Governments also used propaganda, one-sided information designed to persuade, to keep up morale and support for the war. 
Total war meant that governments turned to help from women as never before. Thousands of women replaced men in factories, offices, and shops. Women built tanks and munitions, plowed fields, paved streets, and ran hospitals. They also kept troops supplied with food, clothing, and weapons. Some women saw the horrors of war firsthand, working on or near the front lines as nurses. Although most women left the work force when the war ended, their war efforts were decisive in helping them win the right to vote. After the war, women's suffrage became law in many countries, including the United States, Britain, Germany, Sweden, and Austria. 
The Allies Win the War In March 1917, civil unrest in Russia- due in large part to war-related shortages of food and fuel- forced Czar Nicholas to step down. In his place a provisional government was established. Although the new government pledged to continue the war, the war-weary Russian army refused to fight any longer. Eight months after the new government took over, a revolution shook Russia. In November 1917, the Communists seized power. They quickly ended their country's involvement in the war. In March 1918, Germany and Russia signed the Treaty of Brest-Litovsk. 
Germany turned its attention to the Western Front. In March 1918, the Germans mounted one final, massive attack on the Allies in France. By late May 1918, the Germans had reached the Marne River. Paris was less than 40 miles away. Victory seemed within reach. However, the effort to reach the Marne had exhausted German men and supplies alike. Sensing this weakness, the Allies- with the aid of nearly 140,000 fresh U.S troops-launched a counterattack. In July 1918, the Allies and Germans clashed at the Second Battle of the Marne. Leading the Allied attack were some 350 tanks that rumbled slowly forward, smashing through the German lines. With the arrival of 2 million more American troops, the Allied forces began to advance steadily toward Germany.
 Soon, the Central Powers began to crumble. First the Bulgarians and then the Ottoman Turks surrendered. In October, revolution swept through Austria- Hungary. On November 9, 1918, Germany's Kaiser Wilhelm II stepped down. Germany declared itself a republic. On November 11, Germany and France signed an armistice, or an agreement to stop fighting. World War I came to an end. 
Impact of the War
World War I was, in many ways, a new kind of war. It involved the use of new technologies. It ushered in the notion of war on a grand and global scale. It also left behind a landscape of death and destruction such as was never before seen. Both sides in World War I paid a tremendous price in terms of human life. About 8.5 million soldiers died as a result of the war. Another 21 million were wounded. In addition, the war led to the death of countless civilians by way of starvation, disease, and slaughter. Taken together, these figures spelled tragedy- an entire generation of Europeans wiped out. 
The war also had a devastating economic impact on Europe. The great conflict drained the treasuries of European countries. One account put the total cost of the war at $338 billion, a staggering amount for that time. The war also destroyed acres of farmland, as well as homes, villages, and towns. 
The enormous suffering that resulted from the Great War left a deep mark on Western society as well. A sense of disillusionment settled over the survivors. The insecurity and despair that many people experienced are reflected in the art and literature of the time.