During the latter phase, with lengthy wars of conquest followed by permanent military occupation of overseas provinces, the character of the army necessarily changed from a temporary force based entirely on short-term conscription to a standing army in which the conscripts, whose service was in this period limited by law to 6 consecutive years, were complemented by large numbers of volunteers who were willing to serve for much longer periods. Many of the volunteers were drawn from the poorest social class, which until the 2nd Punic War had been excluded from service in the legions by the minimum property requirement: during that war, extreme manpower needs had forced the army to ignore the requirement, and this practice continued thereafter. Maniples were gradually phased out as the main tactical unit, and replaced by the larger cohorts used in the allied "alae", a process probably complete by the time the general Marius assumed command in 107 BC. (The "Marian reforms" of the army hypothesised by some scholars are today seen by other scholars as having evolved earlier and more gradually.)