Editing Papal States (section)

===Relationship with the Holy Roman Empire===
From the 9th century to the 12th century, the precise nature of the relationship between the popes and [[Holy Roman Emperor|emperors]] – and between the Papal States and the [[Holy Roman Empire|Empire]] – was disputed. It was unclear whether the Papal States were a separate realm with the Pope as their sovereign ruler, or a part of the [[Frankish Empire]] over which the popes had administrative control, as suggested in the late-9th-century treatise ''[[Libellus de imperatoria potestate in urbe Roma]]'', or whether the Holy Roman emperors were vicars of the Pope ruling [[Christendom]], with the Pope directly responsible only for the environs of Rome and spiritual duties.

The Holy Roman Empire in its Frankish form collapsed when it was subdivided among [[Charlemagne]]'s grandchildren. Imperial power in Italy waned and the papacy's prestige declined. This led to a rise in the power of the local Roman nobility, and the control of the Papal States during the early 10th century passed to a powerful and corrupt aristocratic family, the [[Theophylacti]]. This period was later dubbed the {{lang|la|[[Saeculum obscurum]]}} ("dark age"), and sometimes as the "rule by harlots".<ref>[[Émile Amann]] and Auguste Dumas, ''L'église au pouvoir des laïques'', in Auguste Fliche and Victor Martin, eds. ''Histoire de l'Église depuis l'origine jusqu'au nos jours'', vol. 7 (Paris 1940, 1948)</ref>

In practice, the popes were unable to exercise effective sovereignty over the extensive and mountainous territories of the Papal States, and the region preserved its old system of government, with many small countships and marquisates, each centred upon a fortified ''[[Rocca (architecture)|rocca]]''.

Over several campaigns in the mid-10th century, the German ruler [[Otto I]] conquered northern Italy; [[Pope John XII]] crowned him emperor (the first so crowned in more than forty years) and the two of them ratified the [[Diploma Ottonianum]], by which the emperor became the guarantor of the independence of the Papal States.{{sfn|Tucker|2009|page=332}} Yet over the next two centuries, popes and emperors squabbled over a variety of issues, and the German rulers routinely treated the Papal States as part of their realms on those occasions when they projected power into Northern and Central Italy. As the [[Gregorian Reform]] worked to free the administration of the church from imperial interference, the independence of the Papal States increased in importance. After the extinction of the [[Hohenstaufen dynasty]], the German emperors rarely interfered in Italian affairs. In response to the struggle between the [[Guelphs and Ghibellines]], the [[Treaty of Venice]] was signed in 1177. In the treaty, the rights of the Crown in [[Rome]] and in the [[Patrimony of Saint Peter]] were left vague, while papal rights of possession, including the Prefecture of the City of Rome, were recognized but "saving all the rights of the empire".<ref>John B. Freed (2016), ''Frederick Barbarossa: The Prince and the Myth'' (Yale University Press), pp. 404–405.</ref> By 1300, the Papal States, along with the rest of the Italian principalities, were effectively independent.