When Italy went to war on 24^th May 1915, the Cadorna’s plan was unworkable.

Russians, firmly defeated in Galizia, were forced to a dangerous retreat, so that the Austrians could retreat some divisions from that front in order to deploy them in Italy; meanwhile Serbians were in a phase of inactivity, after having begun the conflict with honor.

Because of the lack of the necessary indirect support by the Allies, the Italian initial operations aimed to occupy good starting positions, suitable for easing the additional developments of the original operational plan that they did not immediately give up. In Trentino, the Lizzana-Castel Dante-Corna Calda line was reached; on the uplands the line of the Belvedere-Campo Luserna-Cima Vezzena forts was reached; the Valsugana Borgo and Roncegno were occupied; on the Giulio front the Caporetto basin, the ridge between Isonzo and Judrio, the eastern edge of the Friuli plateau and M. Nero were conquered.

By contrast​​​, the bridgeheads of Tolmino and Gorizia remained under Austrian control.

The initial battles could not give the offensive outlets beyond the Isonzo and the Italian divisions had to stop in front of a continuous defense that was impassable.

General Cadorna reviewed the objectives, aiming for that moment to eliminate the bridgeheads of Gorizia and Tolmino from where the Austro-Hungarian Army could have easily carried out an offensive.

On 23^rd​ June the battle of the Isonzo began and it aimed to eliminate the bridgehead of Gorizia, by acting in three sectors: the positions of Flava, with M. Kuk as immediate target; the Carso, in order to conquer San Michele; the front of the bridgehead​, with the aim of committing the enemy forces.
Gorizia would be surrounded from the north to the south.

The fight has been continuing violently for fifteen consecutive days, but the attempt to conquer M.Kuk failed and Podgora resisted efficiently.

To the south, beyond the Isonzo, the Italians established the first offensive outlets in Sagrado, Fogliano and Redipuglia.

After this first battle, it would have been clear that also in Italy, as in France and the Flanders, the continuity of the front (full of troops) and the equilibrium between the opposing forces imposed a war of position.

Everyone, military and political men, was convinced of breaking the enemy front and being able to pass to a war of movement. Nobody had evaluated the superiority of the defense that was hinged on the binomial netting-machine gun.

After only eleven days of truce, on 18^th​ July the warriors started to fight again along all the Isonzo river. This second Italian offensive was the continuation of the previous one. The greatest effort was done in the sector of the 3^rd Army and, for the first time, there was a great use of the heavy artilleries against the positions of San Michele and San Martino.

The attacks were against the deep valley of Plezzo, the bridgeheads of Tolmino and Gorizia and the Carso. Most of the deep valley of Plezzo was conquered; in the Tolmino area the occupation of M. Nero was increased and the Rombon was conquered. However, the Austrians managed to prevent any progression towards Tolmino. So the Italians attacked on the uplands of Santa Lucia and Santa Maria, but they could not occupy the peaks. They tried to move forward Gorizia from Pavia to Monte Santo, but the violent counterattacks impeded it.

To the south, on the hills along the right bank of the Isonzo in front of Gorizia, the Italians remained at the slopes of the Sabotino, the Peuma, the Podgora, in contact with the enemy armed trenches, without reaching them.

On the Carso the line, that went from the slopes of M. San Michele to M. Sei Busi passing through the eastern edge of Bosco Cappuccio, was occupied.

From 18^th October to 4^th​ November and from 10^th November to 2^nd December, the 3^rd and the 4^th battle of the Isonzo took place on the Giulio front. These operati​ons, that were the same of those on the French front, were decided by the Italian Command in order to relax the pressure of the Austro-Germans and the Bulgarians against the Russian and Serbian Armies.

On 6^th October the Austro-Germany offensive against Serbia began; on 11^th October Bulgaria, allied with the Central Powers, attacked in Macedonia determining the collapse of the Serbian army. The two battles can be considered two different phases of the same operational action that aimed to conquer the middle Isonzo and the uplands above it: the main objective was Gorizia. In half a month of bloody conflicts (the Italian deaths were 116 000 and the Austrian ones were 70 000), the 2^nd and the 3^rd Army managed to damage the enemy defensive system even if they did not break it.

At the same time Italians carried out several local operations with great success​ in Trentino and in Cadore where they fought for the control of Col di Lana.​