Answer
Hi,
The reason could be the misunderstandings over who would be emperor
Step-by-step explanation
Referring specifically to the Empire, most wars were caused by the various sides that competed for power. People revolted due to poor economic times making life difficult for them. Due to unhappy state of citizens, leaders from various sides would use this situation to manipulate the masses, get support and cause a war. Most of these leaders were self-centered with individual interests rather than public representation.
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