In team battles, people often lose track of the defender's advantage. But it always exists.
When a successful push was made, the defender's advantage works based on how many units were lost far away from the nearest factory, how many defenses are in the surrounding area, and how long it takes for an army to respond.
To mitigate the defender's advantage, it is possible to:
1. Build a factory up close,
2. Build static fortresses,
3. Defend important points (from reclaim to mexes)
At the same time, in team battles, communication is key. I encourage players to try and raise awareness of "the enemy & allied" lands, based on how far the fortresses are positioned.
Long story short, remember how Napoleon lost the war!