Once the families discussed in the previous chapter had established their hold on their respective seats of power, the exercise of authority became their goal. In this chapter, the bases on which ducal power was founded will be examined. There was a high degree of common ground between the three duchies, as might be expected from their common background of ruling traditions, but each modified these traditions in the tenth century to suit the needs of autonomous cities. Chief among the priorities of a family such as the Docibilans was the acquisition of control over the lands of Gaeta, as land formed the mainstay of any ruler's power. In all three duchies we see land termed public and private under the control of the rulers, and the origins of the distinction need clarification. At its most basic, land gave a ruler the resource with which to pay for military support. But other factors were present as well, even as early as the tenth century. Rulers associated their heirs in power with themselves, and thereby kept their dynasties in power. There was a notion of the duke as the ultimate source of justice; he derived this status, in part, from the authority that the support of the Church conferred upon him. Yet we need to determine how much support these petty rulers received, and how they cultivated the clergy.