According to Roman military logic, no "legal" war can be déclanchée without a CASUS BELLI. Caesar thus needs to justify its intervention as a Gaulle by the call with helps of a allied nation: Eduens. However, we see here that Eduens are far from being unanimous when with the need for the Romaine intervention. The movement of resistance to the Romans seem even sufficiently important to block the supply of the legions completely. Caesar benefits from it to justify these difficulties with respect to Helvetes (not to say his defeats) by a treason of a part of Eduens which would have to inform Helvètes (what does not seem indeed to be impossible).