[FpUser]

And nearly every soldier playing government side would very likely have relatives on the other side. Most likely great demotivator

[heavyset_go]

Civil wars happen all of the time. Not only is propaganda effective, but militaries have ways to mitigate this, like moving soldiers far away from home to fight in places they don't have familial/cultural/economic/etc ties, which also makes it more likely that the propaganda will work.