1915: June 23
Exactly one month after Italy declared war on Austria-Hungary following the Treaty of London agreement, the Italian army attacked the Austro-Hungarian front line along the Isonzo River.
Germany had pressured its ally Austria-Hungary to take a defensive position in order to save resources for the Eastern Front against the Russians. On top of this the Austrians had long expected Italy’s entry into the war and had made the most of this time by reinforcing their defences.
The region was not well suited for combat, being mountainous and prone to flooding. To succeed, the Italians would have to take down the Austro-Hungarian defensive positions on the mountains above the river, but to do that they would have to cross the river, leaving themselves completely open to attack.
The first attempt came on June 23 after a week-long bombardment of the Austro-Hungarian base. Despite outnumbering their opponents, the Italians couldn’t break though and the Austro-Hungarians soon received reinforcements.
Over the following two years fighting stagnated and degenerated into slow and agonising trench warfare. In total 11 battles were fought on the Isonzo and no substantial progress was made. The Italians suffered around 300,000 casualties in the conflict and the Austro-Hungarians around 200,000.