M21 Sentinel Automated Infantry Unit

"Ratels don't feel hatred, sadness or anger. They are incapable of fear."

- Ratel Drone Operator

The is a UNSC automated infantry unit, a mechanised android used for combat operations. They are used for multiple purposes across the entirety of the UNSC, including patrol, guarding, escort and reconnaissance. A tough, hardy, drone, it is lethal and surprisingly versatile, but only sees limited distribution due to concerns within the UNSC concerning it's use, especially close to civilian populations.

Role
The Ratel is used for a variety of purposes throughout the UNSC. In order to deploy the Ratel, most officers have to go through lengthy documentation, and their calibration must be done on site by specialised technicians. More often than not, their deployment is only precluded by the highest risk to human lives, or where automation is required.

The most common role is that of guard duty. With their enhanced senses and their tireless nature, they make perfect guard dogs, whether at military installations or forward camps. At major installations, such as bases, facilities, laboratories, factories and head quarters, they are a common sight, holding vigil at entrances and patrolling it. In these circumstances, they are usually equipped with a non-lethal weapon, though may have a lethal secondary weapon. They are also used to guard forward operating bases, or other forward sights at risk. Here they'll often be equipped with a lethal weapon with orders to eliminate any threat.

The Ratel is commonly used to patrol in contested or dangerous areas, where it is ill advised to risk human lives. Usually a small team, directly monitored from their home base, will patrol along a predefined route, observing any potential threats and unusual disturbances, but are usually set to only return fire once fired upon. It is preferred that they patrol outside of populated zones, as civilian populations are often frightened of the drones, and there is a constant risk of collateral damage.

Ratels are also used for reconnaissance in force. If it is suspected the enemy may have fortified a position, small units may be deployed to probe the area without risk to human life. Such operations are costly in regards to units though.

Special Forces have been using singularly modified variants in increasing numbers, using them as expendable grunts to inflate their numbers, or as deadly shock troopers in close quarters. These variants often have their processing power boosted by close linked A.I.s, allowing them to perform increasingly complex manoeuvres and work with greater concert.