the Senate and owned much of the empire's land. This in turn bred a feeling of alienation from the army among the Roman aristocracy which in the later 4th century began to resist the military's exorbitant demands for recruits and supplies. Diocletian Diocletian made wide-ranging administrative, economic and military reforms that were aimed at providing the military with adequate manpower, supplies and military infrastructure. In the words of one historian, "Diocletian ... turned the entire empire into a regimented logistic base" (to supply the army). Military command structure Diocletian's administrative reforms had the twin aims of ensuring political stability and providing the bureaucratic infrastructure needed to raise the recruits and supplies needed by the army. At the top, Diocletian instituted the Tetrarchy. This divided the empire into two halves, East and West, each to be ruled by an Augustus (emperor). Each Augustus would in turn appoint a deputy called a Caesar, who would act both as his ruling partner (each Caesar was assigned a quarter of the empire) and designated successor. This four-man team would thus have the flexibility to deal with multiple and simultaneous challenges as well as providing for a legitimate succession. The latter failed in its central aim, to prevent the disastrous civil wars caused by the multiple usurpations of the 3rd century. Indeed, the situation may have been made worse, by providing each pretender with a substantial comitatus to enforce his claim. Diocletian himself lived (in retirement) to see his successors fight each other for power. But the division of the empire into Eastern and Western halves, recognising both geographical and cultural realities, proved enduring: it was mostly retained during the 4th century and became permanent after 395. Diocletian reformed the provincial administration, establishing a three-tiered provincial hierarchy, in place of the previous single-tier structure. The original 42 provinces of the Principate were almost tripled in number to c. 120. These were grouped into 12 divisions called dioceses, each under a vicarius, in turn grouped into 4 praetorian prefectures, to correspond to the areas of command assigned to the four Tetrarchs, who were each assisted by a chief-of-staff called a praefectus praetorio (not be confused with the commanders of the Praetorian Guard, who held the same title). The aim of this fragmentation of provincial administration was probably to reduce the possibility of military rebellion by governors (by reducing the forces they each controlled). Also to this