 Complete the following phrase:  On the Trentino front, the Austro-Hungarians took advantage of the mountainous terrain, which favoured the defender. After an initial strategic retreat, the front remained largely unchanged, while Austro-Hungarian Kaiserjäger, Kaiserschützen and Standschützen engaged Italian Alpini in bitter hand-to-hand combat throughout the summer. In the Alpine and Dolomite fronts, the main battle line led through rock and ice and often to an altitude of over 3000m. The soldiers were threatened not only by the enemy but especially in winter by the forces of nature and the difficult supply. The fighting led to the formation of special units with mountain guides and new combat tactics. The Austro-Hungarians counterattacked in the Altopiano of Asiago, towards Verona and Padua, in the spring of 1916 