In popular culture, we can hear about Roman generals fighting side by side with legionaries. It must be clearly stated that this was not entirely true. The Roman leaders were commanders, not warriors. Only in exceptional situations, when it was necessary, the commander was involved in the fight.
If the battle was defeated, the Roman honor system ordered the commander to draw the sword and commit suicide by hitting himself in stomach with sword or attack the enemy. The first emperor who personally took part in the fight was Maximinus Thrax, reigning in the 235-238 CE.