Recruitment in the Roman Army was a similar process to that in use in some armies today. The applicant was ordered to appear before a board of examining officers, men experienced in the selection of the most suitable fighting material. The ideal was a man six "pes" tall, about 5 ft 10 in, of good eye sight and strong, well-proportioned physique, a man of general good bearing. After passing the board, the man, usually about 18 years old, began a period called "probatio", during which he underwent a stringent period of physical resistance test. His character and personality would also be closely scrutinized during this period, and he would no doubt be asked many questions. Thieves, lazy and immoral men were not welcomed in the Roman Army, and when serious lapses did occur, such as man being caught asleep on sentry duty, they were dealt with very severely indeed, often with fatal results. Once accepted for service, recruits swore an oath of allegiance to the Emperor, probably before the Eagle of his legion.
A large part of the training was devoted to square-bashing and route-marching with full equipment. The Romans exercised great care over rigidity of formation, since this was believed to be the key to safety on the march and success in battle. For marching, the legionaries were taught two kind of paces: a short clipped step called the "military pace", doubtless employed when tight drill was required; and the "full pace", which was a longer easier pace, used on the march for long periods. On the march, the soldiers were expected to cover a distance of 20 Roman miles at the "military pace" in five hours; when the "full pace" was used, a distance of 27 miles was achieved in the same period of time.
Weapon training, of course, was the most important part of the Roman Army military exercises, particularly the correct use of the short sword, or gladius. Recruits were encourage to attack six-foot wooden stakes fixed in the ground, using dummy shields and swords. The Romans used their swords to stab, rather than to slash, keeping the hilt low and thrusting upwards from their hips at the enemy abdominal cavity, probably just underneath the rib cage. Cutting or slashing strokes were avoided as much as possible, since such arm movement would dislocate the formation and would also exposed the soldier right side (the portion of the torso under the right arm). The Romans were said to have despised enemies who laid about themselves with long slashing blades and dispatched them with ease.
The Romans would also be taught to use the legionary shield as a weapon as much as a defense. The boss of the shield was certainly used to punch opponents. Whether or not the javelin had to be delivered with a high degree of accuracy is questionable; the Emperor Hadrian, reviewing troops, praised the accuracy of their throwing, but launching those dreadful weapons at a packed enemy force was bound to do fearful harm wherever those long iron heads landed. Ceasar said that the javelin was capable of piercing the enemies’ shields, proving to be so troublesome to extricate that they preferred to drop the encumbered shields and face the legionaries unprotected.
The recruits were also taught to dig ditches, and build bridges, roads, ramparts, and siege towers. In time, they became skilled construction workers, and their skills were used during peace time, to keep the legions busy and not give them free time to think, to think of uprising.