In 1823, Le Guillou went to the island of Vieques with the intention of purchasing hardwoods. The island at the time had a few residents who were dedicated woodcutters. He was impressed with the island of Vieques and saw the agricultural potential of the island. He returned the following year and purchased lands from a woodcutter named Patricio Ramos. Soon, he established the largest sugar plantation on the island which he named "La Pacience". He then got rid of the pirates and those involved in contraband activities an action which in itself pleased the Spanish colonial government. Le Guillou is considered to be the founder of the municipality of Vieques.