I've discovered a strategy that works best in AOE and ROR, but with less effectiveness on AOK's. I gather about 6 seige engines and I surround them with heavy elephant archers (with lots of armor). I found that you should use at least 6 elephant archers, and, or, a combination of elephant archers, horse archers, and ballistas. This combination of units forms an elite fighting force that can mow down most opponents in its path. The trick is to focus firepower on one or two enemy at a time and try not to be swarmed or overrun. Another good strategy is to use this elite fighting squad to clear everyting close to your enemies' shoreline. You can use a fleet of ships (triremes and juggernauts) to follow and support this elite force - all around the enemies' coastline. It works wonders!! You can also separate the ballistas and archers, from the seige engines (to protect the seige engines), when the enemy threatens to swarm you - trying to destroy the seige engines. You should quey your archer and ballistas to destroy charging enemy with concentrated firepower.