Over the course of half a century, the first two kings of the Saxon dynasty, Henry I (919–936) and Otto I (936–973), waged war across the length and breadth of Europe. Ottonian armies campaigned from the banks of the Oder in the east to the Seine in the west, and from the shores of the Baltic Sea in the north, to the Adriatic and Mediterranean in the south. In the course of scores of military operations, accompanied by diligent diplomatic efforts, Henry and Otto defeated Lotharingians, West Franks, Danes, Obodrites, Weleti, Sorbs, Bohemians, Hungarians, Lombards, and Byzantines, as well as triumphing in the internecine conflicts of East Francia. The end result of more than fifty years of consistent, if not absolute, military and diplomatic success was the establishment of an empire that rivaled in size, population, and wealth that of the great Charles (died 814).

This record of accomplishment, which is virtually unrivaled in both scope and duration from the early ninth to the early nineteenth century in Western Europe, was achieved through well planned and thoroughly organized campaigns that focused on the acquisition of territory over the long term. To achieve these conquests, the Ottonian kings undertook many scores of sieges, including sustained operations that were intended to capture great fortress cities of Roman origin, such as Mainz, Regensburg, Rheims, Senlis, Paris, Pavia, and Rome itself, as well as massive fortresses of more recent vintage that were constructed by various Slavic polities, including Prague, Levy Hradec, Vysehrad, Brandenburg, and Jana.