The war had continued for a week now. As it was a war, that was quite a short period of time. Usually, the individual battles that constituted a war would take place weeks or months apart, but it was different here.
The battles continued constantly. Every time the Heavenly World's people killed a member of the Foreign Race army, the dead would return no more than a day later. In order to cope with the numbers, they adopted a revolving door strategy where they constantly swapped the troops on the frontlines.
The ground troops were able to use this strategy, the arrays of the Krone Clan and their allies like the clans who followed August, and the blessing they received from Thalia's group's progress.
The majority of the world was taken into the True Void Territory at this point. It was highly unlikely for the Vanguard forces to make any progress in destroying the True Void forces.