Complex sentence: Most of Portsmouth's residents, including the mayor, supported the parliamentarians during the English Civil War, though the military governor of the town, Colonel Goring, who commanded the soldiers in Portsmouth, supported the royalists.
Split into simpler sentences: Most of Portsmouth's residents, including the mayor, supported the parliamentarians during the English Civil War. However, the military governor of the town, Colonel Goring, who commanded the soldiers in Portsmouth, supported the royalists.