Holland was just a boy when his father conspired against Henry IV and was attainted and executed. Nevertheless, he was given a chance to serve Henry V in the 1415 campaign in France, where he distinguished himself at Agincourt. The next year Holland was restored in blood and to his father's earldom of Huntingdon, and was made a Knight of the Garter. (His older brother Richard had died in 1400). Over the next five years he held various important commands with the English forces in France and in 1420 was made Constable of the Tower of London. He was captured by the French in 1421 at the Battle of Baugé and spent four years in captivity, not being released until 1425.