Point is: what is the invasion. If he didn't change too much about the people life, then why fighting? To endanger your family? Give the occupation forces reason to attack civil people instead of just be an army fighting another army?
Because that what this kind of behavior will lead to. If some civil take the arms to fight back other army, then the other army will for sure attack the population, something that could maybe have been avoid.
Invasions always result in exploitation of the native people and their resources. Invasions are about conquest, not about having a social tea time with the people.
The Carnival of Shadows - Folk Punk from Asbury Park, New Jersey