Near Thamugadi (modern Timgad), a Roman patrol intercepts a group of Moorish warriors attempting to seize control of a strategic spring. The episode is not attested by ancient sources, but is entirely plausible: in the late 2nd century, Roman outposts in North Africa regularly faced tribal raids, especially when the Empire diverted its forces toward major external crises. Thamugadi, an isolated colonial town at the foot of the Aurès mountains, depended on exposed and difficult-to-defend water sources.

The tactical objective is clear: the Moors are attempting to take control of the spring and the ground immediately surrounding it. If they manage to occupy two of the three key positions by the end of the engagement, access to the water is theirs and the Roman patrol is forced to withdraw. They can also win earlier by inflicting sufficient losses: destroying half of the Roman combat force is enough to break the detachment's resistance and compel its retreat.

For the Romans, the objective is to hold. If the patrol manages to neutralise half of the Moorish force before being too weakened itself, the raid is repelled and order restored. If neither side achieves a decisive result, the Romans retain the advantage through their mere presence on the ground: they hold the spring, and that is enough.