in the 2 village for 300 sec just take over the two outpost on the east north side and then go and hold the village of the north side. on the souther village there will be no attack at all. i did that and it works first help the other king and then help the one with 300 sec for 2 village one.
I too tried and find that romman arrmies are way too powerfull for me in that 500 people mission. i went upto 450 and then my stronghold got doomed. i will try few thing different like collecting peasent before the sequence being started. that way i don't have to worry about romman army. will update you soon