Written in 1542 by a Dominican friar who had watched much of what he describes, this is a reckoning laid before the Spanish crown. Las Casas moves island by island and province by province, beginning with Hispaniola and going on to Cuba, Puerto Rico, the Bahamas and the mainland kingdoms, recording massacre, forced labour, deportation and the emptying of whole regions now silent across thousands of leagues.

The indictment rests on law as much as on pity. The peoples of the Indies were subjects and vassals of Castile, not goods; the papal grant had charged the monarchs with bringing them the faith without inflicting harm; so the settlers' conduct offended divine law, natural law and Castilian law together. He was prepared to argue that they had just cause to make war on the Spaniards.

The pamphlet was one instrument in a campaign he pressed on his king, on the Council of the Indies, and finally on Europe.