The present article is a fragment taken from the thesis work titled “Juan Gines de Sepulveda’s Just War Theory and the Conquest of America” (“La teoria de la guerra justa de Juan Gines de Sepulveda y la conquista de America”), presented at the University Carlos III of Madrid in order to obtain the title of Sufficiency Researcher and an Advanced Studies Diploma. It evidences an implementation of the just war doctrine for justifying the Conquest of America and intends to show some elements that could be useful for analyzing current wars.