This activity brought the Papal States to be a regular country (some authors define it as a theocracy, but this indication is often contested), with a regular army and an intense international political life. Some historians identify in the crowning of Charlemagne the moment in which the Church started having an international importance in a modern sense, while others prefer to see its birth as earlier, at the age of the Byzantine domain on Rome, where the Church already had power and wealth enough to contrast it.
Charlemagne's crowning, however, was perhaps the first moment in which the Church was generally granted a power of control of the imperial dignity, thus demonstrating a sort on power of international veto.
The temporal power has been often discussed in politics, in philosophy and in theology, mainly given that its practical effects were often very far from the official religious doctrine. The same story with the inquisition, quite commonly considered as a mere instrument of the temporal power (therefore with no accepted religious meaning); it is perhaps the moment of the greatest distance between the Gospel and the Roman curia. The common reply to critics usually considers that the final goal of spreading the Good News (working for the diffusion of the Catholic faith), was so important that some "unavoidable" passages had to be crossed, practising at times some of Machiavelli's political lessons.
For practical purposes, the temporal power of the popes ended in 1870 with the completion of the Risorgimento.
Formally, the temporal power ended in 1929 with the treaty between the Vatican State and Italy (Concordat), when the papacy accepted to have no more interests on Italy, its closest neighbour, and therefore on any other country. Of course, the influence of the Vatican still is relevant and evident, even if now it is mostly considered as a merely spiritual voice.
Some small degree of temporal power persists in the formal government of the Vatican City as an independent state.