It’s expensive but effective.
- Leave some worthless troops in a flag. Enough to start a battle.
- Have people online and ready to speed
- Speed the battle and kill them
- Be careful that the enemy is not amassed waiting for this with more people than you have online. Could be a bad outcome.
Sorry but if you have a good enemy and a non spending alliance, you can not win. They will recall if you try to time and target another flag and it’s infuriating. If you try to stack multiple flags then they will speed you and kill you.