André Geraque Kiffer 
Alesia Campaign And Battle, September 52 Bc [PDF ebook] 

In the simulation the Tactic will be as soon as the outer perimeter is broken, the Gauls Army Wing in the oppidum will break — in the same direction, in the opposite way — the inner perimeter. Obtained this junction (First Phase of the Campaign) will be maintained this connecting corridor until the two sectors of the divided Roman Army are beaten in parts (Second Phase of the Campaign). The cavalry will protect the flanks and rear of the Gauls forces against the Roman auxiliary cavalry, and will pursue any Roman forces attempting to retreat.