necessary that both armies should
co-operate, the principle of rotation was adopted, each consul having
the command for a single day--a practice which may be illustrated by the
events preceding the battle of Cannae (Polybius iii. 110; Livy xxii.
41). During the great period of conquest from 264 to 146 B.C. Italy was
generally one of the consular "provinces," some foreign country the
other; and when at the close of this period Italy was at peace, this
distinction approximated to one between civil and military command. The
consuls settled their departments amongst themselves by agreement or by
lot (_comparatio_, _sortitio_), the power of declaring what should be
the consular _provinciae_ was usurped by the senate, (see Senate), and a
_lex Sempronia_ passed by C. Gracchus, probably in 122 B.C., ordained
that the two consular provinces should be declared before the election
of the consuls. At this time the consuls entered office on the 1st of
January (a practice which commenced in 153 B.C.), and their military
command began on the 1st of March. They could hold this military command
until they were superseded in the following March, and thus their tenure
of power was practically raised to fourteen months. But meanwhile the
home officials invested with the imperium had proved insufficient for
the military needs of the empire, and the system of prolonging the
command (_prorogatio imperii_) had been growing up (see Province). The
consul whose command had been prolonged now served abroad as proconsul.
It is probable that Sulla in his legislation of 81 B.C. did something to
stereotype this system. Certainly the government by pro-magistrates
becomes the rule after this period (cf. Cicero, _De natura deorum_, ii.
3. 9; _De divinatione_, ii. 36. 76, 77), although there are several
instances of consuls assuming the active command of provinces between
the years 74 and 55 B.C. (Mommsen, _Rechtsfrage_, p. 30), and Cicero
declares that the consul has a right to approach every province
("consules, quibus more majorum concessum est vel omnes adire
provincias," Cicero, _Ad Atticum_, viii. 15. 3). Certainly in theory the
provinces were still regarded as "consular," not "proconsular," and were
technically, although not practically, held from the 1st of March of the
consul's tenure of office at Rome (cf. Cicero, _De provinciis
consularibus_, 15. 37; Mommsen, _Rechtsfrage_, _passim_). It was not
until the lex Pompeia of 52 B.C. (Dio Cassius xl. 5