Liberating prisons in your main city will allow the construction of various Bases. These bases can only be placed on land that is under your control. From the Map screen, tap the desired tile, tap Details, then Build to see the list of bases that are available for construction.
These bases allow the construction of facilities that are found under the War tab of the build menu. You can also build additional units from these bases and can be used as a strategic offense base or reinforcing defensive base.
Facilities cannot be built on this base, but it can boost the amount of resources that are produced. The land on this base and lands that are one tile away from the base will receive a production boost from its stated value.
Land that is captured by players will all have a default of 100 Field HP. Building this base will boost the Field HP of the land that it is built upon, and can be used to slow down armies that are attempting to reach your strategic bases.
These bases will increase the chance of finding a Ruin surrounding the base. This base can be used to expand the default radius of your home castle and also be built in remote locations from your original location.
Placing catapults will increase the amount of Field HP damage against land or towers that are three tiles away from it. This facility can be utilized for both PvE and PvP purposes.