The Roman Army, 31 BC–AD 337: A Sourcebook

The army in the field 93
column. After these should come the mounted guards (of the legionary
legate) and after these the legionary cavalry, and then the catapults.
(Section 5) Next should come the standard of the fifteenth legion
(Apollinaris) with Valens the commander of the legion, the second in
command, the military tribunes who have been assigned to the
expedition, and centurions of the first cohort (of the legion). In front
of the standard of the infantrymen should be drawn up the spearmen;
the infantrymen should march drawn up four abreast. (Section 6) After
the fifteenth legion the standard of the twelfth legion (Fulminata) should
be positioned, with the military tribunes and centurions around it; this
phalanx (the legion) should also march drawn up four abreast.
(Section 7) After the heavy infantry the allied force should be drawn
up, heavy infantry from Lesser Armenia and Trapezus, and spearmen
from Colchis and Rhizion. After them should be drawn up the infantry
of the [Apulians]. Secundinus, commander of the [Apulians] should be
commander of the allied force. (Section 8) After this should come the
baggage train. The ala of the Dacians and its prefect should form the
rearguard. (Section 9) Centurions who have been appointed for this
purpose should keep the flanks of the infantry in order; to provide
protection the ala of Gauls should ride along both flanks in a single
column, and also the Italian cavalry. Their commander should patrol
along the flanks. (10) The commander of the entire force, Xenophon
(i.e. Arrian), should generally take up position in advance of the infantry
standards, but should also make the rounds of the whole army; he
should ensure that they march according to their formation, bring to
order those who have got into disorder, and praise those who are in
proper formation. (11) This should be the marching formation.
Arrian’s Ectaxis is an account of the military dispositions and tactical
preparations he made for repelling the invasion of the Alani, a nomadic people
living north of the Caucasus, while he was governor of Cappadocia c. AD 135.
It is interesting that he refers to himself as Xenophon, the famous Greek
commander of the fourth century BC. All the military units mentioned have
been identified in Cappadocia except the ‘Aplanoi’, which is probably a
manuscript mistake; the cohort of ‘Apulians’ (known from another source) has
been substituted in the translation. As a description of battle plans the Ectaxis
is a unique document (also text no. 159); see Bosworth 1977; Campbell 1987.
154 Onasander (1st C.AD), prologue 4–7
Finally I may say confidently that my work will be a training school
for good generals and will give pleasure to past commanders in this