During February and March, 1915, the Austrians attempted to dislodge the enemy, but without success. It was now necessary to take those positions before advance could be made against Tarnow, and the Fourth Austro-Hungarian Army, commanded by the Archduke Joseph Ferdinand, undertook the task. At six A. M. on May 2 the Austrian artillery opened fire against Hill 419 from Mount Val (also within the triangle), and the opposite bank of the Dunajec. After three hours' bombardment some regiments of Tyrolese fusiliers, who had crossed the valley between Mt. Val and 419 and had taken up positions at the foot of the latter, about 400 yards from the Russian trenches, were ordered to charge. Dashing up the open, steep slope the fusiliers were suddenly enfiladed from their right by a spray of machine gun and rifle fire, killing many and driving back the survivors. Next day Hill 419 was again fiercely shelled, this time with deadly effectiveness; but even then the Russians still clung to their battered ground. The Austrians now charged the trenches on Hill 412, whence the fusiliers had been ambushed the previous day. A desperate hand-to-hand encounter, in which they had to force their way step by step, finally gave the position to the attackers. The few Russians still left on 419 could not hold out after the loss of 412. They retired northward on to Height 269, but subsequently followed the general retreat of the line. Still farther north, almost at the right flank of Dmitrieff's line, the Austrians effected a crossing of the Dunajec opposite Otfinow, thus breaking the connection between the West Galician Army of Dmitrieff, and the neighboring Russian Army on the Nida--the left wing of the northern groups commanded by Alexeieff. Just below Tarnow, however, the Russians still held out; losing the three hills had not quite broken their defense on the Biala. The right wing of Von Mackensen's army, which had smashed the Russian front around Gorlice, rapidly moved east in an almost straight line to reach the Dukla Pass and cut off the retreat of the Russian troops stationed south of the range between Zboro and Nagy Polena, in northwest Hungary. The left wing, on the other hand, advanced in a northeasterly direction, ever widening the breach made in the enemy's domain. This clever move brought the Germans to the rear of Tarnow and onto the lines of communications of the Russians holding it. It also prevented reenforcements from reaching the truncated end of Dmitrieff's right--or what had been his right--wing. By pushing on to Dembica and Rzeszow, along which route assistance could otherwise have been sent to the Russians, Von Mackensen opened a wide triangle into Western Galicia, by drawing an almost horizontal line from Gorlice to Radymno, between Jaroslav and Przemysl, and from there perpendicular down to the Uzsok Pass.