World War I

World War I began on July 28, 1914, with the declaration of war by Austria-Hungary on Serbia, and hostilities between the Allied and Central Powers continued until the signing of the armistice on November 11, 1918, a period of 4 years, 3 months, and 14 days. The aggregate direct war costs of all the belligerents amounted to about US$186 billion. Casualties in the land forces amounted to more than 37 million (see the accompanying table, World War I Casualties); in addition, close to 10 million deaths among the civilian populations were caused indirectly by the war. Despite worldwide hopes that the settlements arrived at after the war would restore world peace on a permanent basis, World War I actually provided the basis for an even more devastating conflict. The defeated Central Powers declared their acceptance of President Wilson's 14 points as the basis for the armistice and expected the Allies to utilize the principles of the 14 points as the foundation for the peace treaties. On the whole, however, the Allies came to the conference at Versailles and to the subsequent peace conferences with the determination to exact from the Central Powers reparations equal to the entire cost of the war, and to distribute among themselves territories and possessions of the defeated nations according to formulae arrived at secretly during the years 1915 to 1917, before the entry of the United States into the war. President Wilson, in the peace negotiations, at first insisted that the Paris Peace Conference accept the full programme laid out in the 14 points, but finally, in order to secure the support of the Allies for the all-important 14th point, which called for the creation of the League of Nations, he abandoned his insistence on some of the other points.

The peace treaties that emerged from the conferences at Versailles, Saint-Germain, Trianon, Neuilly, and Sčvres were on the whole inadequately enforced by the victorious powers, leading to the resurgence of militarism and aggressive nationalism in Germany and to social disorder throughout much of Europe.