It is never easy to fix upon one cause as the origin of a great war, and the war of 1914 was the outcome of several causes combined. For twenty years there had been growing up in Europe a sense of insecurity; the great Powers had become restless and suspicious of one another, and one Power, Germany, was seriously considering the possibility of some bold stroke which would put her beyond the reach of rivalry. Germany, since her victory over France in 1870, had become a very great and rich nation; she had spread her commerce over the world; and she was anxious to create an empire akin to those of Britain and France. But she began the task too late in the day; she could succeed only at the expense of her neighbours. The ambition of Germany was, therefore, one perpetual source of danger.Another danger was her nervousness, which frequently accompanies ambition. There was an alliance between France and Russia, and a growing friendliness between Britain and France, and Germany feared that her rivals were combining to hem her in and put a stop to what she considered her natural development. Russia had fallen very low after the war with Japan, but was rapidly recovering both in wealth and armed strength. France was making strenuous efforts to increase her army, so that she should not be at a disadvantage as compared with the far greater population of Germany. Britain had no ambitions of conquest; her aim was the peaceful development of her Empire. But that was an oversea Empire, and she required a large navy; and the size of this navy seemed to Germany to be a menace to her future.The result was that in the summer of 1914 the rulers of Germany had decided that some great effort must soon be made; they must put their land in such a position that for the future it would have no cause to dread the aggression, or even the rivalry, of other Powers. If they delayed too long they feared that the growing wealth of Russia and the increased military strength of France would make such an effort for ever impossible.On June 28, 1914, the Archduke Francis Ferdinand, the heir to the Austrian throne, was murdered, along with his wife, in the little Bosnian town of Serajevo. Austria had long been jealous of the movement towards unity among the Slav peoples in the Balkans, with Serbia at their head, and she believed, or pretended to believe, that the murder had been connived at by the Serbian Government. Germany, for reasons of her own, was equally desirous to see the power of the Balkan states diminished. She had a grandiose design of extending her influence eastward through Constantinople to the Persian Gulf, with Turkey as her ally or her tool, and planting a German outpost on the flank of our Indian Empire; and a strong Serbian kingdom, or a union of Slav peoples, would effectually bar the way. With the approval of Germany, therefore, Austria sent an ultimatum to Serbia, demanding certain concessions which would have made Serbia no longer a sovereign state. Serbia, while willing to grant most of the demands, was compelled to refuse others, and Austria promptly declared war.Russia now interfered in support of Serbia, and mobilized her armies on her southern frontiers. Every attempt was made by the statesmen of Western Europe, and notably by the British Foreign Secretary, Sir Edward Grey, to limit the quarrel and to persuade Austria to listen to reason. Germany, however, had no desire for a peaceful settlement. She induced Austria to refuse all mediation, and presently, after a peremptory request to the Tsar to demobilize, she declared war upon Russia. Russia and France were allies, and war with France followed naturally within twenty-four hours.The position of Britain had become extremely difficult She had no formal alliance with France, but in her own interests she could not allow her nearest neighbour to be crushed, and the balance of power in Europe to be entirely changed.