The 1840s are described as a great flowering period for the region's trade. At the same time, like other slave traders, Faber began gradually transferring its interests to peanut and coffee cultivation, although the slave trade continued in parallel. On January 17, 1852, the British and Sierra Leone, in agreement with the domestic ruler, imposed a ban on the slave trade of the region, a ban which the lower river region had already adopted. Mary Faber, who perceived the treaty as a hostile act from the lower river trader in alliance with Freetown's "mulatto" and also as a way of releasing the lower river's Susa tribe from her allied Fula tribe power, which would hurt her business, closed alliance with her colleagues Lightburn and Charles Wilkinson and ravaged the Susu region by the lower river. The war ended with a defeat for Faber and her allies (1855), and her slave fort was burned down. The Faber family rebuilt their fort and continued business. In 1852, Mary Faber handed over the company to her son William Faber, who continued the slave trade until at least 1860. Mary Faber was last mentioned by missionaries in 1857, then only in the role of family matriarch and mother of William Faber.