Excerpts from Books and Wikipedia
"Henry V had embarked upon an ill-judged invasion of Normandy. . . . Hungry, exhausted, and heavily outnumbered--with perhaps 6,000 men against 20,000 to 30,000 French--the English faced almost certain defeat. . . . Agincourt was a military catastrophe for France. About a hundred French noblemen were killed, including thee dukes and seven counts. The cowed French king, Charles VI, recognized Henry as the rightful heir to his throne and gave him his daughter, Catherine de Valois, in marriage. Henry's death in 1422, aged thirty-four, undid all these arrangements, denying the battle any long-term consequences." [1001 Days] "Agincourt was the third of a trio of great English victories--after Crecy and Poitiers--won by English archers over heavily armoured French men-at-arms. . . . However, the total dominance of the English archer was drawing to an end by 1415, with the emergence of gunpowder and the increasing use of firearms." [Battles of the Medieval World]