 On 9 December 1940 the Western Desert Force under the command of Major General Richard O 'Connor attacked the Italian position at Sidi Barrani . The position was captured , 38 @,@ 000 Italian soldiers were taken prisoner , and the remainder of the Italian force was driven back . The Western Desert Force pursued the Italians into Libya , and the 7th Armoured Division established itself to the west of Bardia , cutting off land communications between the strong Italian garrison there and Tobruk . On 11 December , Wavell decided to withdraw the 4th Indian Division and send it to the Sudan to participate in the East African Campaign . Major General Iven Mackay 's 6th Australian Division was brought forward from Egypt to replace it . Mackay assumed command of the area on 21 December 1940 . 
