In 1768, James Grant (1720-1806), Governor of British East Florida from 1763 to 1773, established Grant's Villa Plantation at the juncture of the Guana and North Rivers. Enslaved Africans cleared the 1,450-acre tract of land, planted indigo seeds, and processed the plants into blue indigo dye. Indigo dye became East Florida's main export, and Grant's Villa was its most profitable plantation. By 1780, due to declining soil fertility and the disruption of transportation routes during the American Revolution, indigo cultivation was no longer profitable. Ordered to develop a new estate 12 miles north at the headwaters of Guana River, overseer William Brockie and the slaves completed Mount Pleasant Plantation in 1781. Just south of today's Mickler Road, between SR A1A and Neck Road, the slaves built two earthen dams which enclosed a 220-acre rice field. The dam on the south blocked the flow of salty tidal water. The barricade to the north created a fresh water reservoir. In 1784, following the return of East Florida to Spain, both plantations were abandoned and the enslaved Africans were transported to The Bahamas, from where they were sold to rice planters in South Carolina.