Despite attempts to improve his position and augment his forces by relying on the locally-conscripted Sudanese Defence Force, on local police or on Ethiopian rebels, Major-General William Platt knew that defending Sudan with only three British infantry battalions, no tanks, no artillery and only a handful of outnumbered and obsolete biplanes was a bluff. If only he could delay any enemy attack until the rainy season, and he would be safe, as reinforcements were bound to arrive later. Unfortunately for him, Duke Amadeo di Aosta called his bluff.
All in all, it had been a perfect storm for the Italians – the British had lost a series of ships in the area, and most of their remaining ones (including their last remaining cruiser, HMS Ceres), had been sent on a wild goose chase after the RAMB I. Furthermore, with several of the Sudanese companies being badly mauled in the opening engagements, and with his force of Etiopian rebels almost wiped out, Platt would have preferred to sit back, conserve his forces, and await reinforcements. Political considerations however had forced his hand, and a good part of the 1st Battalion Worchestershire Regiment had been sent south to engage the Italian infantry convoy slowly advancing up the coast – some minor victory was deemed necessary, lest the locals start getting ideas. With the other two British battalions being far away in Khartoum and near the border, this left Port Sudan dangerously exposed, with only HQ company from 1st Battlion, elements of two SDF companies still forming up, some local police and the coastal artillery (manned by Egyptian soldiers) being left to protect the port. This force was deemed sufficient. It was not.
The Italians attacked from three different directions, catching their opponents completely by surprise. It started with a powerful air attack on the port and city center by a combined force of more than 70 aircraft (the single biggest air attack the Regia Aeronautica would conduct in the theater). While actual military casualties were light, the confusion and disorganization it caused greatly aided the follow-up assault. These came from multiple angles – from land, a minor cavalry force, which had been sneaking through the desert for the past weeks,(1) attacked the outer edges of the town, forcing the British commander to deploy whatever forces were at hand against them. This was followed up by an airdrop of approximately 40 paratroopers, (2) literally the whole force the Italians had available, which was carried out on top of the city, as close to the harbor as possible. While these were undoubtebly brave and skilled as infantrymen, they were also grossly inexperienced when it came to carrying out such an operation – nevertheless, they created enough confusion among the defenders trying to organize themselves after the bombing raid that the third and last attack could be carried out. This took the form of a naval landing within the harbor, spearheaded by a couple of fast motorboats packed with marines, and followed up by the destroyers of the Red Sea Flotilla, all filled to the brim with infantry. Owing to the combined efforts of the bombers, the paratroopers and the marines in the motorboats (three of which would end up winning Italy’s highest millitary honor for their action - taking out two heavily defended gun emplacements), only a single piece of coastal artillery remained manned by Egyptian soldiers when the destroyers steamed into harbor. It opened fire on the lead ship, sinking it and forcing the men aboard to swim for the shore. Meanwhile, the other destroyers responded, firing back and forcing the demoralized Egyptians to abandon their gun. With the port now swarming with Italian infantry, the British attempted a counterattack, only to see the Sudanese soldiers flee and blend in with the civilians after it became clear they were massively outnumbered. With no chance of escape, HQ company surrendered after several more hours of fighting, leaving Italy in complete control of Port Sudan.
Under normal circumstances, Platt would have been able to quickly dispatch one of his two reserve battallions to Port Sudan. However, with the rail line having been sabotaged earlier, the redeployment would take time, during which the Italians pushed another convoy through, carrying supplies and artillery. With the landing force now dug in and waiting, the half-hearted counterattack by the British infantry failed to make any progress before being called off.
By itself, the loss of Port Sudan was in no way significant from a military perspective, as the forces used were basically trapped once the RN deployed ships into the area. Politically however, it was a disaster. News of the defeat reached Karthoum almost at the same time as reports indicating that the main Italian formation, the 65th Savoy Grenadiers division, had started advancing from their position at Metema and Kassala straigth for the Sudanese capital. The two Italian flying columns included a fully motorized force, as well as more than half of Italy’s M11/39 medium tanks (3). Duke Amadeo was basically throwing everything he had against Platt’s force.(4) To the average man on the street in Khartoum, it looked like the British were collapsing, just like they were told had happened in Europe. Riots broke out across the capital, at first violently surpressed by the British. Then, when reports arrived that leading elements of the 1st Battalion Essex Regiment and 2nd Battalion West Yorkshire Regiment, along with an assortment of native SDF companies, had failed to stop the Italians (5), Abd al-Rahman and Ali el Mirghani decided there was no point in backing a loosing horse, and ordered their followers to rise up in rebellion throughout the land. Soon, entire SDF companies were dispensing of their British officers and joining their countrymen. William Platt himself was killed, along with Governor-General Sir Steward Symes, after a three-day long siege of their headquarters in the Governor-General's Palace in the centre of Khartoum.(6)
With their supply lines in tatters and chaos raging all around them, the remaining British units in the area were ordered to retreat and regroup north of Khartoum. When the Italian columns finally reached the city, they found the Sudanese in complete control. A few days later, Duke Amadeo di Aosta flew in along with a film crew, and declared Abd al-Rahman to be the new Mahdi (7) and accepting his alliegeance to King Vittorio Emanuele III and the Kingdom of Italy (8)
1 – something like this actually happened OTL, with a cavalry unit raiding Port Sudan
2 – remember those officers Italo Balbo dispatched from his paratrooper training school? This is the result of their efforts to create a similar force in Ethiopia
3 - 15 crappy tanks don’t really seem like much, but when considering that their opponent barely had any AT guns, let alone tanks of his own, they turn out to be a formidable force indeed.
4 - fully motorized and battle-hardened by years of anti-guerrila campaigns in Ethiopia, the Savoy Grenadiers represented Italy’s main (and only) striking force in the region capable of executing such an advance
5 – even though their mission was only to harrass them, which they succeeded in doing actually
6 - the same place where General Gordon was killed by soldiers of the Mahdi
7 – after all, he was the posthumuos son of the famous Muhammad Ahmad, who had captured Khartoum from the General Gordon way back in 1885
8 – although everyone knew that, de facto, the new Mahdi was pledging alliegenace to Benito “the Sword of Islam” Mussolini