Asantehene Prempeh I decides to accept the British's offer to become a protectorate in 1891, becoming convinced (for some reason) that they are bound to lose and the best bet for the Asanteman's survival. Noting the British have a deep belief that the Germans should be kept out of the region, agrees to sign a treaty accepting a British Resident Commissioner (who would also be the Governor of the Gold Coast), in return for weapons, mining advisors, and official recognition as the Paramount Ruler of the Asante. That he should receive a 21-gun salute was a particular sticking point. In return, the Asante proceed to "secure" suzerainty over most of the remaining neighbouring native states (namely the kingdom of Dagomba), thus keeping out the Germans and keeping the British happy.
Prempeh I negotiates with the British over the formation of protectorate over the Asante kingdom.
The start of gold production begins to enrich the Asanteman, and the Asantehene launches administrative reforms, organizing his now-clearly delineated realm into districts that hem in the authority of the local stools in favour of the centre, and helps keep the Germans out thus satisfying the British. He opens an administrative college in the late 1890s to modernise and rejuvenate the already substantial Asante bureaucracy.
This was following the establishment of a British-style secondary school to educate these future bureaucrats, the Asokwa College (now Asokwa Collegiate School). At the same time, certain individuals seen as having command potential—usually sons of military figures—are also sent to Asokwa, and, having joined the cadet unit there, will pursue a military career. Corps Most will be sent on for further education in the United Kingdom or India, and a lucky few at Cambridge or Oxford. Those on a military path will, if lucky, go to Britain and join the Officers' Training Corps at university, and a slim few—at most one or two per year—will be allowed selection to Sandhurst.
Troops of the Ashanti Frontier Rangers on campaign in Togoland, 1915
The Asante military was reorganized into the Ashanti Volunteer Forces (AVF), under British command, but by 1908, under pressure from the three-dozen or so native commissioned officers, it was again reorganized into the Ashanti Defence Force (ADF), which comprised a light infantry regiment, a frontier infantry regiment, a mounted regiment, the guards regiment, an artillery corps, medical corps, engineer corps, and the cadets, totalling to just over 6,000 troops. The ADF is a shadow of the former strength of the Asante army, under the control of the General Officer Commanding, Gold Coast, and run mainly by British officers, but an army nonetheless.
In the First World War several Asante units were sent to fight in Europe and East Africa, which raised the status of the Asante in the eyes of the British, limiting further expansionist tendencies, and leading to the expansion of the ADF and its native officer corps. They also managed to conquer much of German Togoland, and thus effect a 50/50 split of the territory between "Britain" (i.e., the Asante) and the French (rather than the 1/3 and 2/3 division of OTL).
Successive land reform acts, encouraged by the growing class Western-educated of civil servants- one in the early 1900s limiting stool land rights over towns, and a later act providing for freehold tenure for the increasingly significant plantations of cocoa and other cash crops- which increase unrest amongst the local chiefs, thus forcing the Asantehene to return to the more of the traditional power-sharing structure that had previously prevailed, while the more northern and less traditionally Asante regions did not receive this benefit. The emergence of the ADF, however, limited the degree to which central authority could back slide.
Palace of the Asantehene at Kumasi, now the seat of the Paramount Council of State ("Kwasafomanhyiamu"), c. 1914.
A railway was built to connect Kumasi with the Gold Coast's capital and port of Accra by 1910. A plan was laid out for Kumasi and a few other towns, and a few more schools along the British model are opened for the education of the sons of the chiefs and the military and civilian elites alike. The Asantehene had embraced Anglicanism, and missionary schools are opened across the country to spread the faith- and also educate the common people.
By 1920, all of the OTL Gold Coast (less some land in the north and with some land to the east) short of the coastal strip held by the British in 1890, is recognized as part of a burgeoning Ashantiland Protectorate. The economy is growing thanks to growing gold and diamond revenues (even if the British are assuming a large portion thereof), plantations of cocoa and other cash crops, some owned by foreign interests but most in the hands of local grandees, and a rising class of urban merchants. More railways are built, connecting Kumasi to the port of Takoradi, several important mines, and the important northern town of Tamale.
In 1922 the Ashanti Administrative College (as it is by then known) was promoted to the status of a University College affiliated with the University of London, but the Kumasi-based chiefs balk at what they see as strengthening the hand of this new elite, and prevail upon Prempeh to "banish" the new University College to Kuntanase, near the shores of Lake Bosumtwi south of Kumasi. It is joined by a number of other faculties, most notably those of engineering, medicine (with a teaching hospital in Kumasi), and law (although those wishing to practice law must go to the Inns of Court).
In this new period, the country continues to grow, and by 1930 Kumasi is a city of 72,000 residents- far larger than Accra- with several banking houses, markets, schools, a large and imposing palace (on par with that of a middle-rank Indian prince, perhaps), and several lighted streets. Even the houses of the poor are laid out in an organized grid- the neatness of the town surprising foreign visitors used to cities divided between "native" and "colonial" districts of varying quality.
Central Kumasi in the late 1940s.
(this post was longer than I thought, felt I needed the pictures to break it up- there is a second part, that I only need to find pictures for!)