The Ur-Quan Doctrinal War is the method by which the Ur-Quan Kzer-Za and Ur-Quan Kohr-Ah decide whose Doctrine (either the Path of Now and Forever for the Kzer-Za or the Eternal Doctrine in the case of the Kohr-Ah) is superior until the next Doctrinal War. The faction that wins this ceremonial war is allowed control of the Precursor vessel known as the Sa-Matra.
The First Doctrinal War happened following the discovery of the Sa-Matra by the Kzer-Za after the enslavement of the Faz, the destruction of the Yuptar and the near destruction of the Mael-Num. The two sub races agreed to circle the galaxy, enforcing their Doctrines, and when they next met to hold the Doctrinal War again.
It is during one of these wars that The Ur-Quan Masters occurs.