Great masses of Germanic reserves were concentrating in northern Hungary, into which the Russians had driven a thin wedge south of Dukla, where they held an isolated outpost near Bartfeld. To leave this position undeveloped meant compulsory withdrawal or disaster. With the continual influx of reenforcements on both sides, the struggle for the main passes gradually develops into an ever-expanding and unbroken battle front: all the gaps are being filled up. From Dukla westward to the Dunajec-Biala line and the Carpathian foothills a new link is formed by the Fourth Austrian Army, commanded by the Archduke Joseph Ferdinand, with two and a half army corps and one German division. In the Central Carpathians a fifth army, under the command of the Austrian General von Bojna, appears between the forces of Boehm-Ermolli and those of Von Linsingen. Right away eastward the purely Austrian army of Von Pflanzer-Baltin was holding the Pruth Valley. The Germanic chain was complete, with every link welded together.
When the Russian offensive opened on March 19, 1915, the entire battle line still rested on the northern side of the Carpathians, and here the struggle was resumed. The Russian grand attack was directed between the Lupkow and Uzsok passes, where great forces of the enemy, concentrated for the purpose of relieving Przemysl, were stationed. In the western sector, facing Dmitrieff, the Archduke Joseph Ferdinand held the roads leading from Novy-Sacz and Grybow to Tarnow, covering Cracow; and from south of the range the two roads diverging from Zboro to Gorlice and Jaslo were in Russian possession, though the Austrians held their junction at Zboro, eight miles north of Bartfeld. Of the actual fighting that took place in this region very few details were published by the Russian official communiqué. One of these documents, dated April 18, 1915, announced that on March 23, "our troops had already begun their principal attack in the direction of Baligrod, enveloping the enemy positions from the west of the Lupkow Pass and on the east near the sources of the San. The enemy opposed the most desperate resistance to the offensive of our troops. They had brought up every available man on the front from the direction of Bartfeld as far as the Uzsok Pass, including even German troops and numerous cavalrymen fighting on foot. The effectives on this front exceeded 300 battalions. Moreover, our troops had to overcome great natural difficulties at every step. In the course of the day, March 23, 1915, we captured more than 4,000 prisoners, a gun, and several dozen machine guns."
On March 24, 1915, the battle was in full progress: "Especially severe is the fighting for the crest of the mountain south of Jasliska and to the west of the Lupkow Pass. The forests which cover these mountains offer special facilities for the construction of strong fortifications." March 25: "The woods in the Lupkow region are a perfect entanglement of barbed wire ... surrounded by several layers of trenches, strengthened by deep ditches and palisades. On this day our troops carried by assault a very important Austrian position on the great crest of the Beskid Mountains." The Russian captures for the day amounted to 100 officers, 5,600 men, and a number of machine guns. Advancing from Jasliska the Russians seriously threatened the Austro-German position in the Laborcza Valley, to which strong reenforcements were sent on March 25. With terrific violence the battle raged till far into the night of the 27th, the Russians forcing their way to within seven miles of the Hungarian frontier.
In eight days they had taken nearly 10,000 prisoners. By the night of March 28, 1915, the entire line of sixty miles from Dukla to Uzsok was ablaze—the storm was spreading eastward. Like huge ant hills the mountains swarmed with gray and bluish specks—each a human being—some to the waist in snow, stabbing and hacking at each other ferociously with bayonet, sword, or lance, others pouring deadly fire from rifle, revolver, machine gun, and heavy artillery. Over rocks slippery with blood, through cruel barbed-wire entanglements and into crowded trenches the human masses dash and scramble. Here, with heavy toll, they advanced; there, and with costlier sacrifice, they were driven back. Fiery Magyars, mechanical Teutons and stolid muzhiks mixed together in an indescribable hellbroth of combative fury and destructive passion. Screaming shells and spattered shrapnel rent the rocks and tore men in pieces by the thousand. Round the Lupkow Pass the Russians steadily carved their way forward, and at the close of the day, March 29, 1915, they had taken 76 officers, 5,384 men, 1 trench mortar, and 21 machine guns. Along the Baligrod-Cisna road the fighting proceeded, up to March 30, by day and night.
Gradually the Russians pushed toward Dvernik and Ustrzyki south of Lutoviska, threatening the Austrian position in the Uzsok and lines of communications to the south. German reserves were hurried up from the base at Ungvar, but could not prevent the capture of 80 Austrian officers, over 5,000 men, 14 machine guns, and 4 pieces of cannon. Ivanoff had been careful to hold his portion of Selivanoff's army in reserve; their presence turned the scale.
On the day and night of March 31, 1915, the Russians stormed and carried the Austrian positions 4,000 feet high up on the Poloniny range during a heavy snowstorm. So deep was the snow in places that movement was impossible; the trampling of the charging battalions rushing down over the slopes dislodged avalanches of snow, overwhelming both attackers and defenders. By April 1, 1915, the Russians approached Volosate, only twelve miles from the rear of the Uzsok Pass, from which they were now separated by a low ridge. Holding full possession of the Poloniny range farther west, they commanded the road from Dvernik to Vetlina. From the north other Russian columns captured Michova on the Smolnik-Cisna railroad, crossed the Carpathians, and penetrated into the Virava Valley. Occupying the entire loop of the Sanok-Homona railway north and south of Lupkow, and Mezo-Laborcz toward Dukla, the Russians now threatened the Austrian mountain positions between Lupkow and the Vetlina-Zboj road from the western flank as well. Violent winter storms raged across the Carpathians on April 2 and 3, 1915; nature spread a great white pall over the scenes of carnage. While the elements were battling, the weary human fighting machine rested and bound its wounds. But not for long. Scarcely had the last howls of the blizzard faded away when the machine was again set in motion.
South of Dukla and Lupkow and north of Uzsok fighting was resumed with intense vigor. Painfully digging through the snowdrifts the Austrians retired from the Smolnik-Kalnica line, now no longer tenable. Storm hampered the pursuing enemy, who captured the Cisna railway station on April 4, 1915, with all its rolling stock and large stores of munitions.
On April 6, 1915, a Russian communiqué announced that "during the period from March 20 to April 3, 1915, we took prisoners in the Carpathians, on the front from Baligrod to Uzsok, 378 officers, 11 doctors, and 33,155 men. We captured 17 guns and 101 machine guns. Of these captives 117 officers, 16,928 men, 8 guns, and 59 machine guns were taken on a front of fifteen versts (10 miles)."
The Russians again advanced along their whole front on April 4, 1915; forcing their way along the Rostoki stream, they carried the village of Rostoki Gorne with the bayonet and penetrated the snow-bound Rostoki Pass. Their first line arrived at a Hungarian village called Orosz-Russka, five miles from Nagy Polena, at the foot of the pass. The Austrians attempted to drive them back, but they held their ground.
While fortune was steadily following the efforts of the czar's troops in the Lupkow-Uzsok sector, the German War Staff were preparing their plans for the great decisive blow that was soon to be struck. South of the Carpathians, barely thirty miles away, formidable reenforcements were collecting; they arrived from the East Prussian front, from Poland, and even from the west, where they had faced the French and British. There were also new formations fresh from Germany. General von der Marwitz arrived in the Laborcza Valley with a whole German army corps. These gigantic preparations were not unknown to the Russians; they, also, strained every nerve to throw all available reenforcements behind and into the battle line, strengthening every position except one. South of the Lupkow the Germanic forces opened their counteroffensive on April 6, 1915. Official reports on the first day's fighting differ somewhat. The Russians admit a slight German advance, but assert that they were able to withstand all further attacks. The Germans, on the other hand, claim great successes and the capture of 6,000 Russian prisoners.