After the Mahdi drove out Egyptian rule and took over Sudan, he created a Dervish empire. This lasted almost 20 years, until the British-lead (and supplemented) Egyptian forces reconquered the Sudan.
But why did they bother? What use was some mostly desert land to the British Empire? Was it only for revenge of Chinese Gordon (Charlton Heston!)?
As memory serves there were multiple motives.
First, Egyptian Khedival authorities were non-too happy about the Mahdists, whose propaganda wasn’t considered too friendly to them as corrupt collaborators with the
Second, local British army officers were looking for promotions and glory.
Third, there was a sense even up to cooler heads that the Mahdist state was a long-term threat to the Khedival system (whole corruption, collaboration with the foreign imperialists, etc). Remember it was the Ottomans that originally brought Sudan under Egyptian rule and there was, as I recall, a lot of too-ing and fro-ing…
But I bet Tamerlane knows the history better than I, since I am just an imperial history dabbler.
Questions of long-term Imperial policy aside, I shoud think revenge for Gordon would be motive enough to topple the Mahdi. An Empire is not held by allowing such challenges to go unpunished, to take no action could well have been regarded as a sign of weakness by subjects of Imperial rule and might have led to revolts.
Not true, not every loss is worth the cost of punishing, and conquest versus punitive expedition to whack some dervishes are not the same thing. If there was not the long-term threat, London would have had a different reaction.
Politics. It had very little or nothing to do with a threat from the Mahdists themselves and everything to do with contemporary European politics, in particular competition with France. The initial trigger was Adowa, which gave Britain an opening to better relations with Italy, whose now isolated garrison at Kassala was vulnerable and part of the relief involved a diversionary expedition down the Nile. It then spiraled as France and Britain became caught up in the “race to Fashoda”. France had always considered the occupation of Egypt illegal and were sending their own expedition up to Sudan. Under the circumstances Britain felt they had to beat them there and quickly plow through the Mahdists. Revenge for Gordon was bandied about as a motive, but was obviously not a driving concern.
It was all part of the Scramble for Africa, which wasn’t always entirely rational.
Then what could the Khalifa have done to maintain his empire? Make a deal with France? Become a Protectorate?
Not much. Win at Omdurman ( or elsewhere ) and hope his subsequently strengthened position was enough to gain firmer backing from his very ambiguous ally the Emperor Menelik ( then scheming together with the French to seize chunks of the Egyptian Sudan for themselves ) and discourage further Anglo-Egyptian adventurism. That and whole-heartedly embrace a French alliance, which would have bought him the needed modern arms to at least have a better shot at pulling off an Adowa. But he waffled on the last until it was too late. Even if he had accepted French aid, it would have been long odds I expect.
He was pretty isolated and the British were not going to accept him into an alliance - they represented, technically, the Khedival government that wanted the Sudan back and there was the emotive public issue of Gordon’s martyrdom to consider.
They needed a plot for The Four Feathers.
In the short term, it linked Egypt and British East Africa. In the longer term, once Britain acquired German East Africa, it means that Britain has continuous territory between Egypt and South Africa, bring the possibility of a Cape-to-Cairo railway line, even if that project was never completed.
I think they kept the Mahdi’s skull for Kitchener to use as an inkwell but Kitchener didn’t want it and sent it back to be interred along with the rest of his remains. But it ended up being used as an inkwell on some corporal’s desk in Cairo.
The Dervishes were basically 19th Century Taliban who brutally massacred Egyptian and British troops and persecuted Sudanese Christians. They were a blot upon civilization who deserved to be crushed like cockroaches and they got what they deserved at Omdurman (the most satisfactory battle in recorded history, if I may so myself-shame film-making technology wasn’t good enough then to record the battle, we ought to play it to American soldiers heading to the same task in Afghanistan).
?? 19th century Taleban??
Not really.
Of course Egyptian and Empire troops (few were British per se) happily massacred them.
I’ve never read anything particular about the Mahdists forces persecuting the tiny number of Sudanese Copts in those days, although they generally attacked all things associated with the Khedival rule and Egypt, so… (but do you have a source for that, or making it up?)
A blot? Civilisation?
They were a right pain in the ass for the Empire. I don’t know that the Sudanese resistance to the corrupt Khedival rule or even the British empire ‘’ deserved ‘’ to be crushed, let alone by cockroaches.
I suppose dirty wogs and all that.
For what possible purpose? To incite them to do idiotic things to cut your own balls off?
Jaysus.
While your assumed Britishness is quite good, we say arse not ass.
And as I mentioned before in another thread we never ever say vacation when talking about holidays.
I wonder where it is now. That would be one hell of a conversation piece! 
Evelyn Baring had it quietly buried in the Moslem cemetery at Wadi Halfa. Kitchener had contemplated having it turned into a goblet or inkstand, or sending to the College of Surgeons in London.
Most of the posters who’ve been here long enough should be familiar with my views on British Imperialism And The Generally Good Thing That It Was IMHO (With an addendum that I’m well aware a lot of Bad Things happened during the British Empire and it wasn’t all about tea and cricket and having somewhere to hunt tigers), but even I think think this is… an ill-considered and uninformed view of the subject, if I might engage polite euphemism mode for a moment.