Up to the nineteenth century, the Balkan Peninsula was owned by Turkey, but the last century has witnessed the gradual break-up of European Turkey on the Balkan Peninsula. In connection with this disintegration, Russia tried to gain territory at the expense of Turkey. Austria-Hungary also tried to penetrate the same area. A conflict was the inevitable consequence. This Balkan problem had been a source of trouble in Europe for a century. The people of Serbia were Slavs and looked to Russia for support,--in fact, Serbia was practically governed by Russian diplomacy. Austria-Hungary looked to Germany for support. In 1908, Bosnia, which was then a Turkish province but had been administered by Austria-Hungary since 1878, was annexed by Austria-Hungary. This act offended Serbia, who wished to annex it as part of the Pan-Slavic dream for the domination by Russia of Bosnia, Serbia, and the remainder of the Balkans. This annexation by Austria-Hungary defeated the Pan-Slavic dream and was a victory for Pan-Germany. Feeling became more and more acute when in 1914 the Archduke Ferdinand was killed. The incident was applauded by Serbia, and conflict followed. The details of events in 1914 are too complicated to go into for our brief space, but popular accounts reaching the United States were from Allied sources and were correspondingly biased. In 1914 all Europe was divided into two great military camps--the Allied and the Central Powers. The following is the size of the principal armies of Europe in 1914: Germany, 806,000; Austria, 370,000; Italy, 305,000; France, 818,000; Russia, 1,284,000; Belgium, 280,000. All Europe was equipped as a military machine, and the murder in 1914 simply put the machinery in motion. It was an absurd fallacy to think that Germany was the only armed nation at the time, and to believe that Great Britain entered the conflict to defend Belgium is equally absurd. As early as 1911, Great Britain had made plans with France for marching an army through Belgium to Germany in the event of war with Germany. Belgium was regarded as part of the Allied powers. Great Britain has officially acknowledged to be false her ostensible reason for entering the war--the protection of Belgium. Her reason was the struggle between rival imperialisms, which secret treaties later exposed show clearly. However, we are concerned here only with why the United States entered the war. The three outstanding causes were interference with neutral trade, economic ties with the Allies, and Allied propaganda in the United States. These causes overlap in such a way as to make it impossible to discuss them separately.