L.Vorenus and T.Pullo were real characters - appear in Caesar's Commentarii de Bello Gallico.
The episode describes the two as centurions, approaching the first ranks, who shared a bitter personal rivalry, and takes place in 54 BC when the Nervii attacked.
"In an effort to outdo Vorenus, Pullo charged out of the fortified camp and attacked the enemy. Pullo casts his javelin into one of the enemy from a short distance, but his belt is simultaneously pierced by a spear, preventing him from drawing his sword, and he is surrounded by other Nervii. Just then, Vorenus, following Pullo from the fortifications, reached the site of the melee and engaged the enemy in hand-to-hand combat. After slaying one of the enemy and driving back the rest, Vorenus lost his footing on the irregular terrain. As the Nervii drew closer to him, Pullo came to his rescue. After slaying many of their opponents, the two retreated to the fortifications amidst roaring applause from their comrades."
G. J. Caesar