In May 1915 Italy joined the war on the side of the Allies.
Italy had signed a treaty with Germany and Austria-Hungary before the war, creating the Triple Entente. However they had remained neutral so far.
Now Britain, France and Russia persuaded Italy to join them instead. Italy wanted to expand its territory and the Allies offered land in Austria-Hungary as well as German colonies in Africa if she joined them.
Fighting on the Italian Front was mainly in two areas - the Trentino Region and along the Isonzo River. Both of these areas were very mountainous, which made it a very different war to the muddy Western Front.
In June, Italy launched the First Battle of the Isonzo - the first of eleven battles in this area. The goal was to break through to the Austro-Hungarian port of Trieste, which had a large Italian population. The Italian army spent most of the war attempting to achieve this objective - suffering huge numbers of casualties in the process.
Austro-Hungarian soldiers in a trench high above the Isonzo River.