Historian R. E. Smith notes that there was a need to raise additional legions in an emergency to repel specific strategic threats. He argues that this may have resulted in two types of legion. Long-standing legions deployed overseas were probably professional troops forming a standing army. Quickly-formed new legions, in contrast, consisted of younger men, perhaps with little or no military experience, who hoped for adventure and plunder. However, no distinction in basic pay, discipline or armour is known of between the two types of legion. The practice of veteran troops signing up again voluntarily into newly raised legions must have meant that no one army conformed exactly to one or other of these theoretical archetypes.