Complex sentence: However, Cakobau's claim was not accepted by other chiefs, who regarded him as merely the first among equals, if that, and he engaged in constant warfare for almost nineteen years to unify the islands under his authority.
Split into simpler sentences: However, Cakobau's claim was not accepted by other chiefs, who regarded him as, at best, the first among equals. Cakobau consequently engaged in constant warfare for almost nineteen years to unify the islands under his authority.