Board Thread:Questions and Answers/@comment-24567858-20140219184613/@comment-1321146-20140219201534

The invisible attacker must've been their War Marshal, who is indeed invisible until you've defeated (fainted) their Assault Captain and their Defense Captain.

The error in the battle history comes and goes. Sometimes it displays correctly, some times it displays your own guilds name in place of the guild you warred (as you noticed). Also, some times you can tap it to view the battle results, other times you cannot.