1. Attack the fleets with your existing ships in the area and lose them piecemeal while doing little or no damage the maxed out fleets.
2. Retreat all ships in the vicinity to the worlds and take advantage of planetary defenses.
3. Retreat some ships in the vicinity to protect the worlds and slow the advance down, and retreat most of the ships further in so you can ball up and create fleets that can challenge those fleets?
Which strategic choice is the best?