Complex sentence: He ascended to the Irish Peerage as Lord Boyle, Baron of Youghal, 6 September 1616, and was created Earl of Cork and Viscount Dungarvan, 26 October 1620.
Split into simpler sentences: He ascended to the Irish Peerage as Lord Boyle, Baron of Youghal, 6 September 1616. He was created Earl of Cork and Viscount Dungarvan, 26 October 1620.