The Senussi religious brotherhood are based in Libya and have been fighting against the Italian occupation of their country. Now, though, under the influence of Turkish agents they have set their sights on Egypt, where Britain rules indirectly through a client king. The Turks and the Senussi hope to incite a revolt against the British by the Muslims of Egypt, thereby cutting the Suez Canal route from Britain to India.
Today Senussi raiders attack the town of Sidi Barrani in western Egypt. The town is defended by a mixed garrison of Egyptian and British troops, the latter mostly from India. Initial attacks by the Senussi are repulsed but the defenders then decide to retreat away eastwards to a safer location. In the confusion of the withdrawal, however, a unit of Egyptian troops deserts en masse to the Senussi, bringing with them their equipment and camels. British concerns about the reliability of Egyptian troops appear justified. Other Egyptian units are sent away to the east as quickly as possible to prevent them also deciding to join the Senussi.
image source (The Soldier’s Burden)