The fourth battle of the Isonzo was the final Italian offensive of 1915, and made little more progress than the previous three. Both sides had increased the size of their armies on the Isonzo since the start of the third battle in mid-October, the Italians from 19 to 28 divisions, the Austrians from 11 to 15, although the Italians maintained the same ratio of superiority as before
The main targets of this battle were the town of Gorizia, on the eastern bank of the Isonzo, and the Carso plateau to the south. Around Gorizia the Italians twice held and then lost the village of Oslavia, north of the town but on the western bank of the river, and on 29 November captured Oslavia ridge.
On 18 November the Italians began to bombard Gorizia with their heavy guns. Before the start of the bombardment Italian aircraft had dropped leaflets over the town warning the citizens to leave before the bombardment began.
On the Carso the Sardinian Brigade captured Trincea dai Razzi, beginning the slow process of gaining a foothold on the plateau.
The fourth battle of the Isonzo cost the Italians 48,967 casualties and the Austrians 30,000. The first four battles of the Isonzo had cost the Italians 66,000 dead, 190,000 wound and 22,500 captured. The Austrians had lost 165,000 men, but had managed to hold off four Italian offensives, despite being outnumbered by almost two-to-one in each battle. After a three month gap over the winter of 1915-16, the fighting on the Isonzo would begin again in March 1916 with the fifth battle of the Isonzo, the first of five such battles during 1916.