This article examines the influence of formulations and lines of European medieval thought and culture during the two main processes of American political history: the American Wars of Independence and Between the States. In these moments of enormous significance, we can perceive a series of formulations alive since Middle Age centuries; principles with a no evident but relevant influence in mentality and perception during the conflicts. These are: federalism, constitutionalism, canon law, the concept of war, the reception of the work of Dante Alighieri and his ‘Divina Commedia’ and the reception of chivalric medieval culture and the Arthurian tradition.