Wars allow countries to invade & occupy regions for any reasons
To start a war, a country must do the Declare War law against another country
Once the law is accepted, you may begin attacking the country's regions

During a war, President, Vice presidents & Minister of defense may attack enemy regions by:

A region may only be attacked if it is adjacent to one of your occupied regions. In other words, attacks can only be launched from neighboring regions, you cannot attack regions that are separated by another region
If one of your country's Core Regions has been occupied by an enemy, you may launch a Liberation Battle to retake it.

Liberation Battles use a Resistance Bar that determines the damage bonus received when fighting to liberate the region
The maximum size of the Resistance Bar is based on the region's Development:
Resistance Bar = Region Development × 100
Players can contribute to the Resistance Bar by spending either 10 Health or 10 Energy:
The damage bonus depends on how full the Resistance Bar is, The bonus scales proportionally, up to a maximum of +30% damage when the bar is fully filled
For example, if the Resistance Bar is half filled, you receive a +15% damage bonus during the Liberation Battle