The Treaty of St. Germain helped to bring about the end of the First World War and officially resulted in the dissolution of the Habsburg Empire, which had ruled the former Yugoslavian countries, the current Czech Republic, and what are now Austria, Hungary, Poland, and portions of other nations for over five hundred years.
The treaty was signed by representatives from Austria and by representatives of the Allied Powers, which won the war. Austria-Hungary fought on the side of the Central Powers, in an effort to maintain its empire. It is important that the catalyst for the war was the assassination of the Austro-Hungarian Archduke Franz Ferdinand, who was shot by the Serbian Gavrilo Princip.
Austria lost the following territories as a result of signing the treaty: Czechoslovakia, Hungary, Poland, and the Kingdom of the Serbs, Croats, and Slovenes (formerly known as Yugoslavia, but today known as Serbia, Croatia, and Slovenia). Austria also ceded eastern Galicia, Trento, southern Tirol, Trieste, and Istria, which are portions of Spain and Italy, respectively. Istria is a peninsula shared by Italy, Croatia, and Slovenia. The ethnic and geographic diversity of these regions gives some idea of the empire's broad reach and influence.