The "shifting dynamics of power between ruler and dukes" is a major theme of The Salian Century. Under Conrad II conflicts arose around insistence on imperial privileges, the filling of ducal vacancies, where he stressed the hierarchical principle over the hereditary, and disagreements about "foreign policy" with Hungary; he favoured bishops over lay lords. Henry III tried to break up one over-powerful duchy (Lotharingia) and in others kept ducal authority in his own hands. His death probably averted a rebellion, but the minority of Henry IV was only a lull in the conflict: at one point the young king was "kidnapped" by archbishop Anno II of Cologne and his later attempts to exert his power provoked the Saxon War (1073-1075) and the election of an anti-king in 1077. In 1104 Henry V joined the princes against his father, but he soon came into conflict with figures such as archbishop Adalbert I of Mainz. The 1121 Peace of Würzburg illustrated how much had changed over the century, in particular the rise of a notion of "realm" separate from "kingship", a realm for which the imperial princes, joined by the bishops, shared responsibility.
Relations with the papacy started off with the emperors in the ascendancy. Conrad II was crowned by Pope John XIX in Rome in 1027. Henry III elevated papal authority and integrated the papacy into the "Imperial Church System" through the election of German bishops who retained their German sees. He also preferred bishops to lay lords, appointing as bishops clerics trained in the royal chapel. Henry IV came into conflict with the reform papacy under Hildebrand/Gregory VII and was excommunicated in 1076, but though he got the worst of the ideological conflict he prevailed militarily. Henry V's reign saw the Investiture Conflict combine conflicts between the emperor and the pope and between the emperor and the princes (in this case the bishops); the 1122 Concordat of Worms settled this by defining the obligations of the bishops as vassals.
Weinfurter touches on social and economic history where relevant to his thesis. Economic expansion underpinned both Salian power and that of lordships and bishoprics: it is evidenced by a building boom and the spread of fortifications. Salian administration encouraged the rise of a "ministerial" class of warriors and Salian ideology had links with the new tripartite division of society into warriors, workers, and clergy. And architecture and art (generously illustrated with halftones and floor plans) provide evidence for Salian thinking, ranging from the role of the cathedral at Speyer as a dynastic mausoleum to representations of Salian monarchs in books and on coins. Weinfurter does not make external comparisons, but touches on how the constitutional and administrative framework created by the Salians laid the foundations for the Hohenstaufens and the feudalization of the 12th century.