A general Italian advance took place on June 7th across the Isonzo River from Caporetto to the sea, a distance of about forty miles. Monfalcone was taken by the Italians on June the 10th, the first serious blow against Trieste, as Monfalcone was a railway junction, and its electrical works operated the light and power of Trieste.
Next day the center made a great blow against Gradisca and Sagrado, but the river line proved too strong. The only success was won that night at Plava, north of Borrigia, which was carried by a surprise attack. The Isonzo was in flood, and presented a serious obstacle to the onrush of the Italians. By June 14th the Italian eastern army had pushed forward along the gulf of Trieste toward the town of Nebrosina, nine miles from Trieste.
Meanwhile, the Austrian armies were being constantly strengthened. The initial weakness of the Austrian defensive was due to the fact that the armies normally assigned to the invaded region had been sent to defend the Austrian line in Galicia against the Russians. When Italy began her invasion the defenses of the country were chiefly in the hands of hastily mobilized youths below the military age of nineteen, and men above the military age of forty-two. From now on Austrian troops began to arrive from the Galician front, some of these representing the finest fighting material in the Austrian ranks. The chance of an easy victory was slipping from Italy's hands. The Italian advance was checked.
On the 15th of June the Italians carried an important position on Monte Nero, climbing the rocks by night and attacking by dawn. But this conquest did not help much. No guns of great caliber could be carried on the mountain, and Tolmino, which had been heavily fortified, and contained a garrison of some thirty thousand men, was entirely safe. The following week there were repeated counter-attacks at Plava and on Monte Nero, but the Italians held what they had won.
The position was now that Cadorna's left wing was in a strong position, but could not do much against Tolmino. His center was facing the great camp of Gorizia, while his right was on the edge of the Carso, and had advanced as far as Dueno, on the Monfalcone-Trieste Railroad. The army was in position to make an attack upon Gorizia. On the 2d of July an attack on a broad front was aimed directly at Gorizia. The left was to swing around against the defenses of Gorizia to the north; the center was directed against the Gorizia bridge head, and the right was to swing around to the northeast through the Doberdo plateau. If it succeeded the Trieste railway would be cut and Gorizia must fall.