What specific reform did Diocletian introduce to make easier to rule the vast empire of rome?

Answer 1

split it into four parts but kept ultimate power...

Answer 2

Diocletian assigned chiefs for each specialization and he allowed army to retire after 20 years and lowered the price of goods and services and supported agricultural and building and he collected taxes and cultivated land and also created coins.

Answer 3

The emperor Diocletian created the tetrarchy (rule by four) and created four main administrative units (not two) which were called praetorian prefectures. Diocletian appointed fellow general Maximian as co-emperor. Maximian took overall control of the western part of the empire, while Diocletian took overall control of the eastern part. These two men became senior emperors (Augusti) with the creation of two junior emperors (Caesars). The Caesars were subordinate to the Augusti and took charge of defending the troubled frontiers along the rivers Rhine and Danube respectively, which were under constant attack from outside.

The above created the four praetorian prefectures. Diocletian took charge praetorian prefecture of Oriens : eastern Libya (Cyrenaica) Egypt and the territories in Asia. Maximilian took charge of the praetorian prefecture of Italia: Italy and Africa (north-western Africa). One junior emperor (Constantius I) took charge of the praetorian prefecture of Galliae: Britannia and Gaul and Hispania. The other Caesar (Galerius) took charge of the praetorian prefecture of Illyricum: the Balkan Peninsula in south-eastern Europe. These were units of a single empire which, Diocletian stressed, was indivisible.

This reform had several aims: 1) The bad experience of recent sole emperors suggested to Diocletian that sole emperors were vulnerable and that co-emperorship made power more secure. 2) Diocletian had no male issue. Therefore he needed a trusted co-ruler from outside the family. 3) There was a need to improve imperial control over the empire. There had been conflict between powerful men in every province of the empire. Diocletian shared controlling the provinces with Maximian and then the Caesars, too. 4) There was also a need to improve the efficiency of the defence of the vast frontiers of the empire from constant attacks from outside.

The creation of these four units was not a division of the empire which, as Diocletian stressed, was indivisible. It was an administrative arrangement. Co-emperorship was not new. Previously emperors had made their sons co-emperors with one in charge of the east and the other in charge of the east. The purpose was improving the defence of the frontiers. After the tetrarchy, there was an alternation of periods of co-emperorship and periods with a sole emperor. This clearly shows that the empire was not divided.

The creation of rule by four men was accompanied by a doubling in the number of provinces and a tightening of the grip of the imperial bureaucracy over them and local affairs. This enormously increased the size of the imperial bureaucracy and the cost of imperial administration.