In WAR2 Glory a player can control upto 18 cities, but you only start with 1.
By completing Flying High missions, a player can rank up and gain the ability to control more cities.
Flying High missions can be unlocked by completing your Primary Mission category.
Starting at Private with the control of 1 city, you can reach the lofty ranks of Lieutenant-General, with 18 cities under your grasp.
To complete the Flying High mission, you'll need to collect various pieces of precious Jewellery, because apparently Military structure is based on how much 'bling' you own.
These gems can be looted from the Fields outside your city.
Keep checking your Expansion Missions for your next Rank Requirements.
There are currently 18 Ranks in WAR 2 Glory, and achieveing each one grants you the ability to construct a new city.
Private First Class
There are also a number of positions. Position can be handy as it changes what free daily rewards you receive: