Simplify the following text for a Grade 8 native English-speaking person.
Original: A dispute between Hosokawa Katsumoto and Yamana SÅ zen escalated into a nationwide war involving the Ashikaga shogunate and a number of daimyo in many regions of Japan .
Simplified: Hosokawa Katsumoto and Yamana SÅ zen had a conflict that grew into a war throughout the country . The Ashikaga shogunate and some daimyo in many regions of Japan were fighting in this war .