One of the many Overlander AFO ranks, the Decanii are equivalent to a junior officer in UEG military ranks, though their responsibility seems to have been increased greatly over analogues in Earth-based forces.

Decanii are expected to uphold unit integrity. As a result, they are a cross between commissioned officer and morale officer at the same time. However, Decanii are not expected to go to extremes to keep unit strength high, but to keep spirits raised through any means possible which may include propaganda and battle songs. In a fight though, they are all action taking their rank and showing that they've earned it. Indeed, Decanii are chosen for promotion by those that believe they could be a paragon of military strength, which includes at the very least three to five years of military service in addition to an appealing career history. Many figures of prominent Overlander standings, such as the great High General Charlemagne de Silva started his career as a Decanus.

They are positioned over Optios, which fulfill the traditional role of Sergeant, with soldiers referring to them as such sometimes. Optios are expected to keep Decanii up to date on battle statistics as well as good news that can be relayed to troops. Decanii report directly to Centurions, also known as Captains.

Decanii can be thought of as Lieutenants with the easiest of responsibility among officers, though they are still not to be trifled with. Though they may be expected to serve as mouthpieces, they are still deadly combatants. Decanii are also trained to be excellent close-quarters combatants in addition to medium to long range fighting.

During the Great War, companies had as many as five Decanii that kept each unit in shape both physically and mentally. The dark joke in the AFO was that Decanii would carry out Decimation - the execution of every tenth man. Though a source of dark humor, rumors of Decanii taking their duties too seriously have floated through the ranks.

At the war's conclusion in 3224, Decanii, like many Overlander forces, were disbanded when the military collapsed. Decanii have been re-purposed after the starting of the Mabia colony in Alpha Centauri IIb in EUS-0. Decanii became the colony's first police force as they were already adept at reciting law. The challenge was to wean them into a peacetime mindset, which is something First Minister Colin Kintobor has been willing to attempt.

This picture depicts Decanus Rennoc while on an advance through the Great Desert in the West of Northamer. In 3222, a massive army detoured through the desert to head to the south after it was determined that directly assaulting Mobotropolis would be impractical and would create far more casualties. However, sandstorms and incompetent commanders would lead this army to become lost for weeks before getting back on course to what is known today as the Badlands.