Why Sultan Muhammad Imaaduddin IV Refused Supplies to Captain Robert Moresby, and How Local Maldivian Pilots Assisted in the Transition to the Chagos Archipelago Survey.

In the mid-1830s, the Maldives stood at a crossroads between traditional sovereignty and encroaching European imperial interest in the Indian Ocean. The archipelago, with its intricate atolls and reefs, posed grave dangers to shipping on the India-to-Cape trade routes. Captain Robert Moresby, a celebrated British hydrographer of the Bombay Marine (East India Company), arrived in 1834–1836 to conduct the first comprehensive trigonometrical survey of the Maldives.

This mission followed his acclaimed Red Sea work (1829–1833), which had opened hazardous waters to steam navigation and earned him the title "Genius of the Red Sea" from contemporaries like Richard Burton. Upon reaching Malé, Moresby presented official letters from the governments of Bombay and Ceylon, assuring Sultan Muhammad Imaaduddin IV (reigned 1835–1882, during a period of relative stability in the later Utheemu or transitional dynasty phases) that the survey would facilitate safer navigation for vessels calling at the capital and thereby boost local overseas trade.

The sultan, however, saw the proposal in a starkly different light. He refused to provide any supplies, provisions, boats, or official pilots from Male a deliberate act of passive resistance explicitly noted on the resulting Admiralty charts with the annotation "no supplies procurable" at the capital.

The sultan's refusal stemmed from a profound strategic calculation. The Maldives' coral reefs, submerged shoals, narrow channels, and unpredictable currents had long served as the archipelago's primary natural defence.

These hazards deterred invaders, pirates, and colonial powers, preserving Maldivian independence despite the islands' strategic location astride major monsoon-driven trade lanes. Accurate British charts would map every detail, stripping away this protective obscurity and rendering the atolls vulnerable to foreign warships or exploitation. The sultan's fears were well-founded; detailed hydrographic knowledge had already aided British dominance in nearby regions like Aden and Ceylon, and the survey foreshadowed greater interference culminating in the 1887 protectorate agreement that placed foreign affairs and defense under British control. Direct opposition was impossible. The British Empire's regional power made overt confrontation risky, potentially inviting naval retaliation or economic pressure. Instead, Sultan Muhammad Imaaduddin IV chose subtle obstruction: denying state-controlled resources in Malé, imposing bureaucratic delays, and limiting access in central areas under royal authority.

This passive approach frustrated the mission without provoking open conflict. Forced to improvise, Moresby turned to the sultan's political rivals disaffected noble families, atoll chiefs, and factional leaders resentful of central Malé dominance over taxation, trade (cowries and coir), or succession. In outer atolls (especially southern and northern ones distant from the capital), these groups provided essential food, water, local boats, and experienced pilots/guides. This grassroots support enabled soundings, triangulations, and safe harbors, allowing the survey's completion despite official resistance. The arrangement also opened informal channels for discussions, where Moresby likely learned of internal grievances, further heightening the sultan's suspicions of British meddling. The collaboration with Maldivian local pilots proved even more critical when Moresby transitioned southward to survey the Chagos Archipelago in 1837–1838. In the mid-1830s, Chagos was the Maldives' southern frontier, southern gateway, and a crucial stopover in the monsoon-driven Cape Route era. Geologically part of the same Maldives Chagos ridge (with no separate "Lakshadweep" entity at the time the northern islands were known as Maliku, later Minicoy, and historically tied to Maldivian influence), the Chagos (historically called Foalhavahi by Maldivians) lay about 500 km south of Addu Atoll, the Maldives' southernmost point. Pre-colonial Maldivian seafarers from southern atolls used Chagos as fishing grounds, seasonal waypoints, or emergency havens during monsoon voyages, with oral traditions of stranded fishermen rescued from its shores. Though uninhabited at the time (with only feral cats, chickens, and occasional castaways noted on Diego Garcia), the Chagos presented similar challenges: vast submerged reefs (including the Great Chagos Bank, the world's largest coral atoll structure), unpredictable currents influenced by trade winds, and sparse emerged land. Moresby's Maldives experience relying on local knowledge of reef patterns, tidal shifts, and hazard avoidance directly informed his approach. While no large contingents of Maldivian pilots are explicitly recorded as joining the Chagos phase, the continuity was practical and logical. Southern Maldivian mariners possessed navigational insights into the ridge's extension, including monsoon wind patterns that carried vessels southward and behaviour's of similar coral formations. These pilots, having assisted in the Maldives survey (and benefiting from its charts, which Maldivian navigators favoured until the 1990s), likely provided informal guidance or recommendations for the southward leg. Their expertise bridged the two archipelagos, aiding safe entry to atolls like Peros Banhos (where Moresby Island bears his name) and Diego Garcia (where he planted 30 breadfruit trees).Moresby's Chagos work produced the first thorough scientific charts, with detailed soundings, reef outlines, and notes on seasonal tides/currents. His observations later informed Charles Darwin's 1842 coral reef theories. The assistance from Maldivian pilots—forged amid tension in the Maldives ensured accurate mapping of this extended coral system, vital for Indian Ocean trade safety. Ultimately, Sultan Muhammad Imaaduddin IV's refusal highlighted a ruler's strategic caution in defending sovereignty against imperial science. By denying central support, he preserved short-term autonomy but could not halt the advance of British hydrographic dominance. Meanwhile, the pragmatic alliances with local pilots not only sustained Moresby's mission but extended its benefits southward, blending indigenous expertise with colonial cartography in a remote oceanic frontier. This episode remains a telling chapter in the Maldives' navigation from isolated independence toward colonial entanglement, underscoring Chagos' role as an integral southern extension rather than a detached entity in the pre-colonial maritime world.