when the northern border heights would be crossed and the entry to Asia Minor effected by way of Karahisar. There are no difficulties to traffic along this avenue. On the other hand, an advance from Mush, the side of the southern depression, could only be undertaken by mountain paths above the course of the Murad, which have never been touched by an engineer. It is therefore probable that the tide of war would be diverted for some time to the lowlands, when it might threaten the south-eastern districts of Asia Minor from the side of Diarbekr. On three occasions, all during the course of the present century, Erzerum has been at the mercy of Russian armies. In 1829 it was actually taken by Marshal Paskevich, whose troops penetrated as far north as Gümüshkhaneh and to within eighteen miles of Trebizond. [178] Recovered by Turkey at the ensuing peace, it was threatened by a similar fate after the fall of Kars in November 1855. It was only saved by the Russian reverses in other quarters and by the early termination of the war (Treaty of Paris, March 1856). In 1877 the Russians forced the Deveh Boyun barrier, which in those days was unprovided with proper defences; but they met with a serious repulse in an attempt to storm the forts on the eastern flank of the enceinte. The investment was not completed until the month of January 1878; and, although the place was held by their armies as a material guarantee during the negotiations for peace, it was retained by the Sultan under the terms of the treaties of San Stefano (March 1878) and Berlin (July 1878). Since the conclusion of that campaign the advantages of the position have for the first time been turned to proper account; and, if in the future the system of forts should be found provided with the most modern ordnance and held by a sufficient garrison, Erzerum may still earn the glory of owing her preservation to the sword rather than to the pen.