thats just theory in reality you will loose 1 CC after your single attack because of simultaneous turns. no chance to move in and get out. 5 spears will eat your CC at breakfast. MP is not like fighting a stupid KI. and as i said build walls of units, at best behind 1 tile away from a river
for cities, build them at hills, build a wall and you will stay much longer.
OH OK all you have to do is start in the best possible defensive terrain, spam spears right from the beginning, and build all cities on top of hills and with city walls. Right- perfectly balanced! Of course, if Greece decides to just contain you with the CC and expand aggressively, you're screwed, but never mind that...