Those biremes killed all they could, but didn't die as transports don't fight in battles.Thanks a lot for the answer!
ad1 - yes he had lots of transport ships and I had only 4 biremes left - still, why didn't those 4 biremes fight until the end?
ad2 - ...so he should have fought my remaining biremes with the help of breakthrough
ad3 - no, he did not
thanks