Civilizations that fell because of internal dissention were big examples because they were so big that there was no threat from outside. When there is not outsi

Civilizations that fell because of internal dissention were big examples because they were so big that there was no threat from outside. When there is not outside enemy, one is created within to suit the needs. Not to mention internal strife can invite and give another party an opening. See US before/after WW2/Cold war, or Rome before/after Punic wars