Complex sentence: Robert Maxwell, 5th Lord Maxwell (1493--1546), Was Regent of the Isle of Arranand through marriage to his second wife Lady Agnes Stewart also made the Maxwell's a minor house of the royal House of Stuart.
Split into simpler sentences: Robert Maxwell, 5th Lord Maxwell (1493--1546), Was Regent of the Isle of Arran. Through the marriage to his second wife Lady Agnes Stewart also made the Maxwell's a minor house of the royal House of Stuart.