College of Electors and of the College of Princes (see below). The ruler was required to agree to accept imperial taxation and military obligations. Furthermore, the Estate was required to obtain admittance into one of the Imperial Circles. Theoretically, personalist Estates were forbidden after 1653, but exceptions were often made. Once a territory attained the status of an Estate, it could only lose that status under very few circumstances. A territory ceded to a foreign power ceased to be an Estate. From 1648 onwards, inheritance of the Estate was limited to one family; a territory inherited by a different family ceased to be an Estate unless the Emperor explicitly allowed otherwise. Finally, a territory could cease to be an imperial Estate by being subjected to the Imperial ban (the most notable example involved the Elector Palatine Frederick V, who was banned in 1621 for his participation in the Bohemian Revolt). In the German mediatization between 1803 and 1806, the vast majority of the Estates of the Holy Roman Empire were mediatised. They lost their imperial immediacy and became part of other Estates. The number of Estates was reduced from about three hundred to about thirty. Mediatisation went along with secularisation: the abolition of most of the ecclesiastical Estates. This dissolution of the constitution of the structure of the empire was soon followed by the dissolution of the empire itself, in 1806. Rights and privileges Rulers of Imperial States enjoyed precedence over other subjects in the Empire. Electors were originally styled (Serene Highness), princes (high-born) and counts (high and well-born). In the eighteenth century, the electors were upgraded to (Most Serene Highness), princes to (Serene Highness) and counts to (Illustrious Highness). Imperial States enjoyed several rights and privileges. Rulers had autonomy inasmuch as their families were concerned; in particular, they were permitted to make rules regarding the inheritance of their states without imperial interference. They were permitted to make treaties and enter into alliances with other Imperial States as well as with foreign nations. The electors, but not the other rulers, were permitted to exercise certain regalian powers, including the power to mint money, the power to collect tolls and a monopoly over gold and silver mines. Imperial Diet From 1489 onwards, the Imperial Diet was divided into three : the Council of Electors, the Council of Princes and the Council of Cities. Electoral states belonged to the Council of Electors;