British hegemony in the Persian Gulf, often referred to as its “informal empire,” relied on a small number of British diplomatic and governmental officials, which rarely numbered more than a dozen, backed by the military power of a half-dozen or so British ships of war. British involvement in the Persian Gulf dates back to the early 17th century, when the British East India Company sought to secure valuable trade with Iran. As abortive as those attempts often were, Britain began to assume a hegemonic role in the Persian Gulf only in the early 19th century when the region’s strategic importance and the issue of slavery necessitated a larger British role in the region.
Initially, British efforts were directed at restricting the slave trade away from India, but gradually assumed a greater geographic scope after Britain’s military intervention against the Qasimi in the early 1820s. Initially, British efforts to disrupt the East African slave trade relied on undermining demand for slaves in Oman and other areas of the Persian Gulf by securing agreements with local rulers whereby those rulers would be responsible for interdicting the slave trade on their shores. This optimistic plan inevitably ran aground of the inability and disinterest of various local rulers to stringently enforce their agreements.
The British then sought to interdict the trade themselves in the 1850s and 1860s, using authority granted to them by local rulers to search and seize vessels found to be engaged in slave trading, but the handful of British ships of war were ultimately insufficient to identify and interdict slave trading vessels as they passed into the Persian. British efforts to disrupt the slave trade were also complicated by Britain’s reluctance to disrupt slavery as a social institution, which remained legal as a domestic institution throughout the Persian Gulf despite local rulers’ commitments to disrupting the slave trade and the importation of new slaves into the region.
Consequently, British naval strategy shifted in the early 1870s from attempting to disrupt demand to disrupting supply, which culminated in Zanzibar’s 1873 abolition of the slave trade and British naval patrols at Zanzibar and along the Tazanian coast to disrupt supply. This last strategy was ultimately successful in disrupting a significant proportion of the East African slave trade, although the trade continued into the early 1900s. Later shifts in supply, such as in the exportation of slaves from the Makran Coast in the first decades of the 20th century, postponed the demise of slavery in the region until the mid 20th century, and was only abolished in Oman in 1970.