The Sentinel is an infantry unit, available in the Digital Age, being the next infantry unit after the Marine. Sentinels are the first Ranged Infantry which wields laser weapons, and wear a science fictional white uniforms and a full white helmet, with black boots. The uniform arms and tip of the helmet are colored as the player colour.
This unit is quite effective against Citizens and other infantry. They're quite brutal in numbers, and even better so in the company of Gladiator Tanks. They are more like underground terrorist.