Before the Empire's troops appeared, the Alliance did not wish to dispatch their main forces into battle.
But sometimes, affairs do not unfold as anticipated, and that is exactly the case right now.
The force and intensity of the Rebel Army's offensive far exceeded expectations, proving too much for the regular members of the Alliance to withstand. Even in the Tulip City War Zone, where the situation seemed most favorable, there was only a stalemate, and that was thanks to Wilton's personal command and the efforts of his Alliance Army. Compared to that, the other war zones performed poorly, partly due to being outnumbered, and partly because the Alliance Army had yet to mobilize.
In such a situation, calls for the Alliance to send troops quickly emerged in all Four Great War Zones, but they were suppressed by the zone commanders.