Mary, Queen of Scots had just married James Hepburn, Earl of Bothwell on 15 May.
Bothwell offered single combat to any of the Scottish lords. Several lord took him up on his offer, but he refused them.
Within a year, by 1568, Mary would divide the country and a war would start over her that would last for 5 years.
Shakespeare may have imagined that perhaps one day he would meet this James, Mary's son, in person, and perhaps even perform a play for him.
Because little did Shakespeare know that the Battle of Carberry Hill, like the Battle of Langside, and all of the other slings and arrows that Mary suffered, were battles that were never resolved in the heart of James, and they haunted him his entire life.