John of Eltham, 1st Earl of Cornwall was the second son of king Edward II of England and his queen Isabella of France.
Background
He was heir to the English throne from the date of the abdication of his father (25 January 1327) to the birth of his nephew Edward, the Black Prince (15 June 1330). John was born in 1316 at Eltham Palace, Kent. Caught in the throes of the war between his father, Edward II, and mother Isabella, his growing years were turbulent.
Career
At the age of twelve, he was created Earl of Cornwall on 6 October 1328. Information on John is scant, but by most historical accounts he was highly competent, and highly trusted by Edward. He was named "Guardian of the Realm" when Edward III was out of the country.
Was asked to open Parliament in Edward"s absence, and was named Warden of the northern Marches, which gave him virtual autonomy in that portion of England.
Half a dozen brides had been proposed for him, most being the eligible daughters of the kings of Europe. Eventually, Maria, illegitimate daughter of Afonso IV of Portugal was chosen, but John died before the marriage.
At seventeen he was a key commander in the Battle of Halidon Hill (1333), a devastating defeat for the Scots. Later he commanded an army in the southwest of Scotland that put down resistance to Edward Balliol, whose claims to the Scottish throne were supported by England.
According to Scottish accounts, who view John as a ruthless destroyer, he burned down Lesmahagow Abbey when it was filled with people who had sought sanctuary from the wrath of the English troops.
According to modern historian Tom Beaumont James, this tale "challenges the distinction between history and story." John died, shortly after turning 20, at Perth, probably from a fever. Arms As Earl of Cornwall, John had use of the coat of arms of the kingdom, differenced by a bordure France (ie azure semy of fleur-de-lys or).