 Sanford remained loyal to the Belgian king until 1889, when serving as the American representative at Leopold's Anti-Slavery Conference, Leopold betrayed his earlier free trade plans for the Congo and asked for the imposition of customs duties so as to aid the destruction of slavery in the Congo.His efforts on overseas matters resulted in his Florida groves failing as a lucrative business.To meet his labor shortages, Sanford brought 100 workers from Sweden, agreeing to pay for their passage after one year of labor.