For Serbia, then, her entrance into The Balkan League in 1912 was a natural sequence of many of her previous aspirations and efforts. In presence of a common danger--the Teuton working through the Turk--the Balkan States put aside their own particular rivalries and formed a Union. This was effective, and the Turks were defeated. But when Turkey was defeated, Bulgaria and Serbia were again at sword's points. It was not a question of jealousies between small kingdoms, but rather a larger issue--Pan-Slavism as against Pan-Teutonism. Serbs, wherever found, were outspoken, and Austria saw that she might have to give up not only her hope of adding Serbia to her dominions but besides this lose her dominion over the Serbs within the dual monarchy. From that time she hardly tried to hide her intention of punishing Serbia for her ambition. Serbia, meanwhile, was growing bolder, stronger. Though her successes in recent wars had not given her her coveted seaport, she had found ways of getting a considerable proportion of her products to market without sending them through Austria. Her imports from Austria fell off largely. Austria and Germany saw that they would have difficulty in making Serbia a docile ward, especially as M. Pachich in 1912 had made it plain to the other Powers that it would be to their advantage to give Serbia a chance to expand.
It was eleven years almost to a day from the time he came to the throne, when Peter's security was shattered by an explosion. The Archduke Ferdinand, heir to the Austrian throne, and his wife, while making a tour through Bosnia, were killed at Sarajevo by a Serb, not one of the kingdom of Serbia but a Serb of Greater Serbia. Austria, that had been for so long watching Serbia as a cat watches a mouse, quickly pounced on the little kingdom. She made demands such as no civilized country could comply with, and at last gave an ultimatum on the twenty-seventh of July which had far-reaching consequences. It was a stone thrown into a quiet pool and the ripples and eddies reached unthought-of shores, as the whole world now knows.
There are many strange circumstances connected with this murder. Those who have followed out the various clues have seen evidence that the Serb government had no knowledge of the proposed murder, but there is much that tends to show that the assassination was not a great surprise to Austria--that Ferdinand, even at home, was in fear of his life. He always slept in a room without furniture and not long before the assassination he had taken out a life insurance, the largest life insurance known. In case of his death, it was necessary to make provision for his consort who could hope nothing from the house of which he had long been the heir. When Ferdinand's heir had a son born to him, the Austrians turned against Ferdinand and wished him out of the way. His removal, indeed, was a greater object to Austria-Hungary than to Serbia, for it was generally known that he was liberal in his ideas regarding the Serbs in the dual monarchy, and had even formed a plan for giving them Home Rule.