 In this context, the Protestant Reformation (1517) may be viewed as a schism within the Catholic Church.German monk Martin Luther, in the wake of precursors, broke with the pope and with the emperor by the Catholic Church's abusive commercialization of indulgences in the Late Medieval Period, backed by many of the German princes and helped by the development of the printing press, in an attempt to reform corruption within the church.Both these religious wars ended with the Peace of Westphalia (1648), which enshrined the concept of the nation-state, and the principle of absolute national sovereignty in international law.