The 4th SAI are involved in the advance across the desert to Sollum. There is little to no water on the 50-mile march from Bagbag and the march becomes known as the Thirsty March. They arrive at Sollum on 15th March to find that the 1st and 2nd had already arrived and had prepared tea for them. The brigade spends time constructing a road to the plateau above Sollum. This road would become a key highway for the British forces in World War 2.