If you were really into RP, you would shoot such a battleship yourself so that it would start pummeling you for the duration of the battle. This has the added effect of giving allies to the proper players. If your enemies are hopelessly outnumbered on their own ground, it might be nice to give them some NPC aid.
Even if they aren't outnumbered, you could still pop a few shots at a corsair titan if you are attacking Crete (which seems to happen every day).
