This abolitionist text surveys the role of the Spanish press in influencing public opinion on slavery in Puerto Rico and Cuba, and putting pressure on the Spanish government to abolish slavery. The importance of public opinion, "our great weapon"(3), is demonstrated in the case of the reformist project of Moret in 1870, which was opposed both by the colonialists and by many abolitionists for its cautious approach to gradual abolition. This short text contains a survey of the public response to the project, the text of the proposed law, and extracts from the press responding to the law.