Two Autobot leaders fell during the war that ensued, and Sentinel Major inherited the Matrix of Leadership and became Sentinel Prime, leader of the Autobots. Sentinel Major survived this clash, but he and the rest of his race-now dubbed 'Autobots'-were robbed of any chance of peace when the military hardware robots, now known as ' Decepticons', set their sights on conquering Cybertron for themselves. Subsequently, the consumer goods robots rose up against the Quintessons in a rebellion that ultimately forced the aliens off the planet. He was once defeated in battle by Prima, who attacked their Quintesson masters when their match was over, only to be destroyed himself. Unusual among his consumer goods brethren, Sentinel Major was equipped for combat and was forced to participate in gladiatorial games for the Quintessons' amusement, wielding a spiked ball-and-chain weapon and a tire-shaped shield. Sentinel Major was originally one of the Quintessons' slave robots on Cybertron around twelve million years ago. Likewise, the earlier appearance of 'U-Haul Robot' was dubbed 'Sentinel Major', giving him a pre-Matrix name.

The character is referred to as U-Haul Robot in the dialogue script for 'Five Faces of Darkness, Part 4' and was not given the name 'Sentinel Prime' until The AllSpark Almanac II declared it so via an Ask Vector Prime entry. The original cartoon version of Sentinel Prime was never named in fiction.

Matrix sentinel scene