On the 12th the Russians gained an important success by capturing Sokal, which lies on the River Bug, just across the frontier. The town is an important railway centre, and its possession was a matter of vital interest to Austria. A determined advance towards Vladimir Volynski was a definite part of the Austrian programme. If successful, the move would have had far-reaching effects, for it would have broken the railway between Rovno and Warsaw, and so seriously impeded the completion of the Russian mobilisation and render communication between her central and southern armies very difficult. For this advance Sokal was the only possible base of operations. The Austrians, therefore, defended the town to the utmost of their power. The passage of the Bug was fiercely contended, but after some hours of furious fighting, during which both sides lost heavily, the Russians managed to capture the bridge. This practically settled the engagement. The town was unfortified, and at the mercy of the attacking force. The Austrians, with the dreaded Cossacks in pursuit, were soon in headlong flight out of the town. The destruction of the railway station and bridge rendered the Austrian advance in this direction impossible for some considerable time. When, therefore, on August 17th, a general advance was ordered, Russia had every reason to be satisfied with the state of affairs. True, the enemy had established themselves in Poland, but this was more than balanced by the advances into Eastern Prussia and Galicia. Russia indeed had achieved more than she had reckoned on. During this preliminary phase she had fully expected that Poland would be invaded. She had also expected that her right and left flanks would have been more or less seriously threatened by forces from Eastern Prussia and Galicia during the most difficult process of mobilisation. The forces at Kovno and Rovno were sent to deal with that menace, and to hold it in check until the main armies were ready. They not only achieved that object, but carried the attack into the enemies’ countries. CHAPTER V THE ADVANCE INTO EASTERN PRUSSIA