Complex sentence: In 1646 James Graham, 1st Marquess of Montrose laid siege to the Castle Chanonry of Ross which was held by the Clan Mackenzie and took it from them after a siege of four days.
Split into simpler sentences: In 1646 James Graham, 1st Marquess of Montrose laid siege to the Castle Chanonry of Ross which was held by the Clan Mackenzie. Graham took it from the Mackenzies after a siege of four days.