Catholics and the Negro.
1917 article from the Journal of Negro History by Joseph Butsch, arguing that the Catholic church was crucial in ammeliorating the condition of slaves in the Americas.
Let My People Go: the Catholic Church and Slavery
An article looking at the Catholic church's nuanced attitude towards slavery - allowing it in some cases but condemning the harsher version practiced in America and the English colonies.
On Manumission and Redemption
Pope Gregory I (c. 600) not only set free serfs subject to him but he awarded them the goods they held, and he put forward the strongest reason for his act. From the Medieval Sourcebook.
On the Abolition of Slavery
Encyclical of Pope Leo XIII promulgated on May 5, 1888.
Prohibition on Selling Christians to Pagans for Sa
From Pope Gregory III in 731.
Thomas J. Murphy, Jesuit Slaveholding in Maryland,
Book review by Maura Jane Farrelly.