Complex sentence: Montgomerie's campaign razed some of the Cherokee Lower Towns, including "Keowee", but it ended with a defeat at Echoee ("Itseyi") Pass, when Montgomerie tried to enter the Middle Towns territory.
Split into simpler sentences: Montgomerie's campaign razed some of the Cherokee Lower Towns, including "Keowee". It ended with a defeat at Echoee ("Itseyi") Pass when Montgomerie tried to enter the Middle Towns territory.