Complex sentence: On their return home they were ambushed by the Clan MacKintosh at Clachnaharry, where the Battle of Clachnaharry ensued and many lives were lost on both sides.
Split into simpler sentences: On their return home they were ambushed by the Clan MacKintosh at Clachnaharry. The Battle of Clachnaharry took place and many lives were lost on both sides.