In the meantime the Russian center continued its advance against Erzingan. This is an Armenian town of considerable military importance, being the headquarters of the Fourth Turkish Army Corps. On March 16, 1916, an engagement took place about sixty miles west of Erzerum, resulting in the occupation by the Russians of the town of Mama Khatun, located on the western Euphrates and on the Erzerum-Erzingan-Sivas road. According to the official Russian statement the Turks lost five cannon, some machine guns and supplies and forty-four officers and 770 men by capture. Here, too, however, the Turks began to offer a more determined resistance, and although the official Russian statement of the next day, March 17, 1916, reported a continuation of the Russian advance towards Erzingan, it also mentioned Turkish attempts at making a stand and spoke even of attempted counterattacks. This stiffening of Turkish resistance necessitated apparently a change in the Russian plans. No longer do we hear now of quick, straight, advances from point to point. But the various objectives toward which the Russians were directing their attacks--Trebizond, Erzingan, the Tigris--are attacked either successfully or consecutively from all possible directions and points of vantage. Not until now, for instance, do we hear of further advances toward Erzingan from the north. It will be recalled that as long ago as February 23, 1916, the Russians occupied the town of Ispir, some fifty miles northwest of Erzerum on the river Chorok. The headwaters of this river are located less than twenty-five miles northeast of Erzingan, and up its valley a new Russian offensive against Erzingan was started as soon as the new strength of the Turkish defensive along the direct route from Erzerum made itself felt. On April 1, 1916, and again on April 12, 1916, the Turks reported that they had repulsed attacks of Russian scouting parties advancing along the upper Chorok, and even claimed an advance for their own troops. But on the next day, April 3, 1916, the Russians apparently were able to turn the tables on their opponents, claiming to have crossed the upper basin of the Chorok and to have seized strongly fortified Turkish positions located at a height of 10,000 feet above sea level, capturing thereby a company of Turks. Again on the following day, April 4, 1916, the Russians succeeded in dislodging Turkish forces from powerful mountain positions.