After Persia invading my lands, I did an invasion of 6 MA's next to Persia(newly captured India) myself, made RoP and MpP's with every nation except Persia. Before Persia attacked me, I got attacked by Mongols! They killed my 6 MA's, and my great leader I just produced there, and I killed like 20 cavalries and 20 medieval infantries. Persia did attack me, captured a stupidly undefended city of mine, and moved with the invading troops of his.
I killed the invaders, needless to say, and got back my city.
I call this the world war.
IROQUOIS GREECE ENGLAND AMERICA HITTITES vs PERSIA MONGOLIA SPAIN
Troops:
IROQUOIS: Mech Inf, Modern Armor, Jet Fighter, AEGIS Cruiser
GREECE: Mech Inf, Tank, Bomber, Destroyer
ENGLAND: Cavalry, Infantry, Man-O-War
AMERICA: Infantry, Cavalry, Frigate
HITTITES: Cavalry, Infantry, Tank
PERSIA: Mech Inf, Tank, Battleship, Destroyer, Bomber, TOW
MONGOLIA: Cavalry, Medieval Inf, Longbowman, Rifleman
SPAIN: Longbowman, Warrior, Pikeman, Spearman
Luckily I didn't have a

moment yet
I invaded Persian mainland, and destroyed a city. I do not look forward to capture and defend policy against Persians.
I have destroyed the city next to Persepolis(Gordium I think) and I'm marching with 3 MA armies towards the capital.