With the installment of Byzantine Emperor Kantakouzenos, The Byzantine Civil War begins. Lasting until 1347, his ascension was questioned by so-call “Pretender”, John V. Losing thousands of men and territory, Kantakouzenos will be allowed to retire to a Monastery (and live out the remainder of his life).
High hills divide bloody enemies. Each has enough resources, and enough space to build his castle. Give them enough resources in the beginning, and great battles are upon you.