The contubernium was the smallest organized unit of soldiers in the Roman Army and was composed of eight legionaries, the equivalent of a modern squad. The men within the contubernium were known as contubernales. Ten contubernia were grouped into a centuria. Soldiers of a contubernium shared a tent, and could be rewarded or punished together as a unit.
The contubernium was, at least very late in the period (though it is possible the title existed in the late republic and early principate) led by a Decanus, who might crudely be described as the equivalent of a junior non-commissioned officer, however there is no evidence of a decanus exercising any kind of battlefield command role, regardless of any responsibilities they may have had in garrison or camp. They were presumably appointed from within the contubernium and were most likely the longest serving legionary. Their duties would likely have included organising the erection of the marching tent and ensuring their tent-mates kept things tidy.[better source needed]
Two auxiliary "servants", vaguely equivalent to modern logistical support troops, were assigned to each contubernium. They were responsible for the care of the contubernium's pack mule, making sure that the legionaries had water during the march, and may have had special skills like blacksmithing or carpentry (however legionaries often fulfilled specialist roles so it is very possible that they were simply grooms and servants.) There were 10 contubernia (8 men) each led by a decanus, in a century (100 men including 20 support staff) which was commanded by a centurion.