After creating the Chimaeric Demon eggs, Erik and his group had left the area, but their impact brought waves. It had set in motion a chain reaction that reshaped the battlefield largely.
The group didn't see the impact first hand, since they were far from the battlefields, but as they traveled from base to base, reports trickled in of the Chimaeric Demons' advance.
Essentially, the clones had infiltrated the enemy underground base, replacing soldiers and stealing strategic intelligence.
This stolen information helped Frant's forces a lot, because armed with insider knowledge, they dismantled the blackguards' carefully laid plans in that sector.
However, that helped other parts of the front lines too, and it made it so the various groups of fighters could push the front lines further north.