What are the motifs in Dark Force Rising by Timothy Zahn?

Loyalty is a major theme. In Dark Force Rising virtually no one on the Imperial side of the war holds any loyalty to its cause. The officer corps is, of course, obedient to the chain of command, but there is animosity between ground troops and the naval elite. The only partial exception is the Noghri, who believe themselves beholden to the late Darth Vader for helping them partially overcome the ecological devastation of their planet. Leia Organa Solo is able, however, as "Lady Vader," to shake their loyalty to his viceroy, Grand Admiral Thrawn.