Italy felt that the best time to attack in Africa was when the British were busy with the Battle of Britain. Mussolini ordered Marshal Rodolfo Graziani, to launch an attack into Egypt immediately.
On September 13, a large element of Graziani's Italian Tenth Army crossed the border between Libya and Egypt, and advanced into Egypt as far as Sidi Barrani. Sidi Barrani was about 100 kilometers(60 Miles) inside Egypt from the Libyan border. The Italians then stopped and began to entrench themselves in a series of fortified camps.
At this time, Britain had only 30,000 troops available to defend Egypt against 250,000 Italian troops. However, the Italians were not concentrated in one place. They were spread out from the Tunisian border in western Libya, to Sidi Barrani in Egypt.
On December 8, 1940 the British Operation Compass began. General Richard O'Connor pressed the attack forward and succeeded in reaching El Agheila (an advance of 500 miles) and capturing tens of thousands of enemies. The Allies nearly destroyed the Italian army in North Africa, and seemed on the point of sweeping the Italians out of Libya. The Italian managed to halt the British advance in February of 1941. German General Erwin Rommel now became the Axis commander in North Africa, however the bulk of his forces consisted of Italian troops.
As in Egypt, the Italian forces with ~70,000 Italian soldiers and ~180,000 native troops outnumbered their British opponents. But Italian East Africa was isolated and far away from the Italian mainland. The Italian forces in East Africa were thus cut off from re-supply. This severely limited the operations that they could seriously undertake.
The initial Italian attacks in East Africa took two different directions, one into the Sudan and the other into Kenya. The Italian forces advanced into the two countries, but not very far. Most units only advanced a few miles, occupying the border posts.
In August 1940, the Italians advanced into British Somaliland. On August 14, the Italians began to encircle the British defenders from their eastern positions, and the defenders' situation started to look critical.
After three days of battle, early on August 15, Godwin-Austen (fearing encirclement) concluded that further resistance at Tug Argan would be futile. He contacted the British Middle East Command headquarters in Cairo, Egypt and requested and received permission to withdraw his forces from British Somaliland. By August 17, the entire colony had fallen into Italian hands.
After the fall of British Somaliland, General Archibald Wavell's plan for the counter-offensive by British and Commonwealth forces included a "northern front" led by Lieutenant-General William Platt and a "southern front" led by Lieutenant-General Alan Cunningham. A third front would be created by the forces which would re-take British Somaliland by sea.
In January 1941, British forces launched a counter offensive. From Sudan in the north, Platt advanced into Eritrea on 19 January. Battling through mountainous territory, his forces reached the heavily garrisoned town of Agordat, 160km (100 miles) from their start. On 28 January it fell after two days of bloody fighting.
Platt now made for the town of Keren, 80km (50 miles) away and the gateway to Eritrea's central plateau. The route lay through the Dongolaas Gorge, a wild, craggy area where progress was only possible after enemy forces were dislodged from the commanding heights. RAF units based inside Eritrea provided air support. Platt's forces fought to the coast at Massawa, 160km (100 miles) away, and took it on 8 April. Within the next few days, Eritres had been occupied.
At the same time, Italian East Africa was also attacked from the south. In Kenya, Cunningham assembled a force of three divisions, one South African and two composed of Nigerian and Ghanaian troops under British officers.
On 10 February, Cunningham led part of his force east from Kenya into Italian Somaliland, while the remainder marched north into Abyssinia. The Italian Somali capital of Mogadishu fell on 26 February and by 5 March the Italians were routed. The town of Jijiga in north eastern Abyssinia, 1,600km (1,000 miles) from Cunningham's Kenyan starting point, fell on 20 March. On 6 April Cunningham's reunited forces entered the Abyssinian capital Addis Ababa. The Duke of Aosta surrendered on 16 May, but some isolated Italian forces fought on until 27 November.
Emperor Haile Selassie, along with British troops , crossed the border from Sudan on 20 January and made for Addis Ababa, harassing the Italians and enlisting support from local rebel groups. Their advance was outstripped by Cunningham's, however: Wingate and the Emperor first entered Addis Ababa in a victory march on 5 May, about a month after Cunningham. After the fall of Addis Abba the British mopped up the remaining Italian resistance in the area. Although organized Italian resistance was halted, a guerrilla war would carry on until 1943.
A seesaw war began in North Africa. The Axis forces pushed the British back into Egypt under Rommel, but they were soon forced back into Libya. In 1942 the Axis forces once again advanced, pushing within just 60 miles of Alexandria. The Axis in spring 1942 seemed on the verge of sweeping the British out of Egypt, however at the First Battle of El Alamein (July 1942) General Claude Auchinleck halted Rommel's advance and the Allies assumed the offensive with the Second Battle of Alamein (October/November 1942) under General Bernard Montgomery. The Axis forces began a long retreat all the way back to Tunisia.