Edmund of Lancaster, 1st Duke of Lancaster, KG (3 March 1423 – 26 January 1448) was an English nobleman and member of the House of Lancaster, the second of four surviving sons of King Henry II and V and Catherine of France.
Edmund, groomed in his position to rule as Regent of England, was married to Margaret of Scotland in 1438 at the age of 14. By all recorded accounts, the young marriage was happy; however, Edmund's desires to crusade in Spain left her as regent of his lands in England on many occassions. A miscarriage in 1445 left her ill.
In 1448 on a return from Paris, Edmund was beset with fever in Harfleur.[a] He died nearly a week later; his death sparking a civil war.