108 Chapter 6
given responsibility for the west, with another, Con-
stantius, serving as caesar in Gaul and Britain. In recog-
nition of its greater wealth and importance, Diocletian
took the east for himself and established his headquar-
ters at Nicomedia in Asia Minor. His trusted lieutenant
Galerius was made caesar with special responsibility for
Syria and Egypt.
Decentralization worked well as long as the author-
ity of Diocletian remained intact (see map 6.1). He was
probably right in assuming that no one man could effec-
tively govern so vast and beleaguered an empire. If Max-
imian and the two caesars remained loyal, they could
respond more quickly to crises without losing control of
an army that numbered more than 650,000 men. To en-
sure even quicker response, the army was divided into
permanent garrisons and mobile expeditionary forces.
The latter, reinforced with heavily armored cavalry
(cataphracti) on an unprecedented scale, were capable of
moving rapidly to threatened sectors of the frontier.
To separate military from civilian authority, Dio-
cletian assigned each augustus and caesar a praetorian
prefect with broad judicial and administrative powers.
He then subdivided the existing provinces, increased
the civil powers of their governors, and grouped the
new, smaller units into diocesessupervised by imperial
vicars. The vicars reported to the praetorian prefects.
The new administrative system would be the model
for the later empire—and for the Christian church
when it eventually achieved official status. Diocletian
used it primarily to implement economic reforms. ToNARBONENSISElbe
R
GERMANYDamascusBlack SeaRed
SeaAtlanticOceanNorth
SeaBaltic
SeaAdriatic
SeaMedi
terran
ean SeaDanu
be R.Rhine
R.Ni
le
R.Ebro
R. RhoneR.Dniepe
rR.
DonR.RomeAlexandriaSardiniaCorsicaSicilyCreteCyprusRavennaBalearicsCarthageCorinthAthensSyracuse RhodesPergamumConstantinopleAntiochJerusalemAdrianopleDA
LM
AT
IACISALPINE
GAULPHRYGIAASIAJUDAEAEGYPTSaharaNORTH AFRICAGAULNUMIDIALIBYASYRIACAPPADOCIATHRACEMOESIADACIABRITAINMAURETANIANEARERSPAIN
FARTHERSPAINNORIC
PAN UM
NON
IAMACEDONIALine of division
between East
and WestSein
eRPyrenees
Mts.AlpsMts.CILICIATierb.R0 200 400 Miles0 200 400 600 KilometersPrefecture of Gaul
Prefecture of ItalyPrefecture of Illyricum
Prefecture of the EastMAP 6.1
Divisions of the Restored Roman Empire. c. 300