After a prolonged siege, Omani forces captured Fort Jesus at Mombasa, marking a decisive erosion of Portuguese power on the Swahili Coast and strengthening Oman’s western Indian Ocean maritime reach.
Saʿīd ibn Sulṭān emerged as the dominant ruler of Muscat and Oman, a political foundation that later enabled tighter control over Zanzibar and the East African coast through naval power, trade, and appointments.
In an anti-slavery agreement with Britain, the Moresby Treaty sought to curb the movement and sale of enslaved people in the western Indian Ocean, signaling growing British leverage over Omani/Zanzibari maritime commerce.
Saʿīd ibn Sulṭān’s visit to Zanzibar helped consolidate his authority there and coincided with early investments in clove cultivation that would later transform Zanzibar’s plantation economy and regional trade networks.
Saʿīd ibn Sulṭān took Mombasa, reinforcing Omani dominance over a key Swahili Coast port and strengthening the coastal chain of control that supported customs revenues, shipping, and commercial expansion inland.
Saʿīd ibn Sulṭān moved his capital (court) from Muscat to Stone Town, making Zanzibar the operational center of an empire whose prosperity increasingly depended on maritime trade, plantations, and coastal-inland commercial routes.
The Hamerton Treaty (negotiated by Atkins Hamerton) prohibited certain exports of enslaved people from Zanzibar (notably toward the Persian Gulf), representing another step in Britain’s incremental strategy to constrain Indian Ocean slaving routes.
Saʿīd ibn Sulṭān died at sea, creating a succession dispute that culminated in the formal political separation of Oman and Zanzibar—an important turning point for the East African maritime domain’s governance.
An internationally recognized settlement (often associated with Canning arbitration) formalized the independence of the Sultanates of Muscat (Oman) and Zanzibar, shaping Zanzibar’s later trajectory as a coast-and-islands maritime state.
Under heavy British pressure, Sultan Barghash signed the Frere Treaty, which prohibited the import of enslaved people into Zanzibar’s dominions and compelled closure of Stone Town’s public slave market—though illicit trafficking continued.
Britain and Germany signed the Heligoland–Zanzibar Treaty, redefining spheres of influence in East Africa; Germany recognized British authority in Zanzibar in exchange for other concessions, accelerating Zanzibar’s subordination to British control.
What remained of the Zanzibar Sultanate was proclaimed a British protectorate, institutionalizing British dominance over external affairs and deepening political oversight that would culminate in direct interventions in succession and administration.
Following a disputed succession, British warships bombarded the palace, defeating Sultan Khalid bin Barghash in what is widely cited as the shortest recorded war; it demonstrated the decisive military leverage underpinning the protectorate.
Omani Empire's East African maritime domain (1698–1896)
