The 23rd Armed Rangers of the 3rd Expeditionary Army was a division of clone troopers that contained the 300th Flight Battalion, a mechanized airborne unit. The 23rd Armed Rangers were given this unique moniker because they were composed of clone troopers that graduated from Ranger school, a combat training camp dedicated to small-unit tactics. The camps were headquartered in the low gravity Polis Massa system and the standard gravity Borel system.
The Republic recognized a need for rapid-deployment infantry force that could mobilize immediately to defend or capture a planet. In lieu of a space trooper corps to defend ships from boarding and capture, the force was also trained in basic close-quarters combat aboard vessels.