Regarding the runaway Spanish slaves, he wrote a covering letter to Cochrane on March 9, attached to 'a representation from the Inhabitants of Pensacola respecting their losses'.

Writing from HMS Royal Oak, off Mobile Bay, on March 15, 1815, Rear Admiral Pulteney Malcolm, Cochrane's subordinate commander of the Mobile Squadron, assured Manrique that Post-Captain Robert Cavendish Spencer (a son of George Spencer, 2nd Earl Spencer) of HMS Carron, had been detailed to conduct a strict enquiry into the conduct of Lieutenant Colonel Edward Nicolls and Captain George Woodbine, regarding the property losses of Spanish inhabitants of Florida.

He told them that new orders meant they could no longer be transported to British territory, and warned them that he foresaw future vengeful behavior on the part of the Americans.

[10] Later, in July 1815, de Soto complained that the Negro Fort, left armed by the British, had become a refuge for "villains of all classes and Nations," and was impacting the region's trade.

He subsequently ordered a delegation to Prospect Bluff to recover Spanish-owned slaves and gather intelligence on the forces still under British command.

In a letter dated August 19, 1815, de Soto requested from Pintado, the surveyor general, a duplicate copy of the plan of Pensacola.