I clear it at normal ai. U don't need to build dock, wall just forcus to your infantry,
U need to build an oracle as fast as possible. Build about 4,5 mystery and everything will be more simple.
Build sparatie with javelin and shield, hoplite with long sword and shield.
Stay near the gold mine in the south-east. When u have about 20-30 units, ah don't forget the catapult, 1 or 2 is ok, only need to break the wall, then u only need to go on the land, fight from bottom to the top.
Enemy sometimes will invade by the sea, but its number is few, i only need 3,4 infantry and they all dead. forcus on the land. U realy don't need the ships.
Everytimes a soldier hp is low remmeber to get it near the mystery, select all mystery to auto heal.
Researh only javelin, curved shield, long sword, u only need the best. It's will save your gold, get weapons droped by your helos, sell them for gold.
Try to defend at the gold mines at south-east until u can build some mysterty, spatantie with javelin and shield. It's the hardest time in this mission. Always keep your unit close each other, don't get near the wall until u decide to do the final blow.
Hope this will help , sorry for my E.