As noted above in the commentary to the Prologue, this scene serves, first, to emphasize the contrasting attitudes between the French camp — their joviality and overconfidence and superficiality — with the prevailing seriousness of the English camp. In contrast to the frivolity of the French, the entire scene in the English camp is essentially serious. Yet, there is an anticipation of great humor when the disguised king exchanges gloves with Williams and promises to meet him in a duel if they both survive today's battle; we anticipate Williams finding out that he was arguing with the very monarch for whom he is fighting.
The main purpose of this scene is to further illuminate the character of King Henry on the night before the significant and decisive Battle of Agincourt. Any time that a king wraps himself in a cloak and goes among his men incognito, talking with the common soldiers, we have a very dramatic situation. Continuing a dramatic device of the earlier Henry plays, the rowdy and rebellious Prince Hal had to, at first, disguise himself to become a king; now as king, he disguises himself to become a common man. Now wrapped in the obscurity of a commoner's cloak and further obscured by the darkness of night, the king is able to learn the feelings of his common soldiers, represented not by the comic Pistol (who knew the king as Prince Hal) and not by the dedicated, if peculiar, Fluellen (and Gower), but as seen in the personages of John Bates, Alexander Court (even though this character speaks only eleven words in the entire play), and Michael Williams. Even the names "John Bates" and "Williams" suggest something of the basic nature of these good English soldiers — that is, this is the stuff of which an ideal Englishman is made of and which will help Henry win military glory for England.
