had one medium, two mixed and four light tank battalions on the escarpment and were redeployed to the coast road. On 9 September, the Maletti Group got lost en route to Sidi Omar and Rodolfo Graziani cancelled a flanking move and concentrated on the coast road, with five divisions and the Maletti Group; the 4th CC.NN. Division "3 Gennaio" and 64th Infantry Division "Catanzaro" divisions stayed in reserve at Tobruk. The 5th , a mixed air unit with about 300 serviceable aircraft, airfield equipment and transport, stood by to support the advance and occupy airfields. The Italian invasion of Egypt on 13–18 September began as a limited tactical operation towards Mersa Matruh, rather the strategic objectives sketched in Rome, due to the chronic lack of transport, fuel and wireless equipment, even with resupply from the 5th Army. Musiad was subjected to a "spectacular" artillery bombardment at dawn, then occupied. The 1st Libyan Division took Sollum and the airfield. By evening the 2nd Libyan Division, 63rd Infantry Division "Cirene", the Maletti Group from Musaid and the 62nd Infantry Division "Marmarica" from Sidi Omar, pushed past British harassing parties and converged on Halfaya Pass. The British withdrew past Buq Buq on 14 September and continued to harass the Italian advance. They fell back to Alam Hamid the next day and to on 16 September. An Italian force of fifty tanks attempted a flanking move so the British rearguard retired east of Sidi Barrani, which was occupied by the 1st CC.NN. Division "23 Marzo" and Graziani halted the advance. The British resumed observation and the 7th Armoured Division prepared to challenge an attack on Mersa Matruh. Despite prodding from Mussolini, the Italians dug in around Sidi Barrani and Sofafi, about west of the British defences at Mersa Matruh, repairing roads demolished by the British, cleaning wells and beginning work on a water pipeline from the border, accumulating supplies for the resumption of the advance in mid-December. Egypt broke off diplomatic relations with the Axis and Italian aircraft bombed Cairo on 19 October. British naval and air operations to harass the Italian army continued and caused damage which prisoners reported had lowered morale. Armoured car patrols dominated no man's land but a lack of landing grounds reduced the effectiveness of the RAF and Malta was out of range. Operation Compass, a British counter-attack to an Italian advance on Matruh, planned to destroy Italian forces