Complex sentence: The first creation in the Scots Peerage came in 1580 in favour of Esme Stewart, 1st Earl of Lennox who was created Duke of Lennox at the same time.
Split into simpler sentences: The first creation in the Peerage of Scotland came in 1580 in favour of Esme Stewart, 1st Earl of Lennox. He was created Duke of Lennox at the same time.