In 1390 Scrope accompanied John Beaufort, half-brother of the future King Henry IV, on the Barbary Crusade to Mahdia, but otherwise little is known of his early life. An annuity granted to him by King Richard II was continued by Henry IV after Richard's deposition, and in 1403 Scrope was styled 'king's knight', and fought on Henry IV's side at the Battle of Shrewsbury. His uncle, Richard Scrope, Archbishop of York, was executed on 8 June 1405 for taking part in the Northern Rising against the King; however Henry Scrope was not involved in his uncle's failed rebellion, and was serving the King in Wales when he inherited his father's title and lands in 1406. In 1408 he accompanied Henry IV's daughter, Philippa, to Denmark for her marriage, and in 1409 went to Paris on a diplomatic mission with Henry IV's half-brother, Henry Beaufort.