The Peace of Augsburg was established in 1555 following the German Wars of Religion, which were fundamentally about the Protestant Reformation and its impact on Christian unity. This treaty was significant because it allowed rulers in the Holy Roman Empire to choose either Lutheranism or Catholicism as their realm's official faith, leading to a degree of religious tolerance. However, it also reinforced the principle of cuius regio, eius religio, which established that the religion of the ruler determined the religion of the governed, thus setting a precedent for future religious conflicts and divisions in Europe.