Being able to efficiently live on another planet and cultivate it and possibly more will help greatly. The main things wars are generally fought over are: land, religion/beliefs, resources, and an idea of inferiority. So basically if we start being able to live well on multiple other planets it will eliminate 2 of the 4. (Land and resources) at some point we'll be able to dedicate planets to farming oil mining things like that where these planets are very viable for things such as this for example a planet or planets dedicated to drilling for oil or one for farming rice...