With his noblemen in attendance, Henry sends for the archbishop and asks him to explain the Salic law, which will tell him whether he has a valid claim to the throne of France. He demands an honest assessment, since he knows the heavy cost in blood of any war. He asks that the cleric speak with a clear conscience.

The archbishop embarks on a very long, probably deliberately obscure speech about the Salic law.  According to the Salic law, no woman could transmit a claim to the French throne. This was decided by French nobles in the fourteenth century, when the English King Edward III claimed the throne because he was the son of Isabella, the daughter of Philip IV of France. Philip had no other direct descendents following the death of his third son. The archbishop argues that this law applies only to German, not to French lands. He adds that many a French king owes his crown to descent through the female line. Therefore Edward III's claim to the French throne was valid, and could be lawfully renewed by Henry V, his descendent.

The archbishop's explanation is as clear as mud, and Henry impatiently asks whether he would be in the right if he were to make this claim. The archbishop uses a quotation from the Bible to further buttress his case. He then urges Henry to fire up his martial spirit and go to the  tomb of his ancestor Edward III from whom his claim derives. He also urges Henry to visit the tomb of Edward III's son, Edward the Black Prince, who won a great victory on French soil. Ely lends his support, urging the King to repeat the great military feats of his ancestors. The Dukes of Exeter and Westmoreland add their encouragement, emphasizing Henry's strength and the rightness of his cause. Canterbury then announces his offer to donate a large sum to the crown.

Henry responds by pointing out that they must also arm themselves to defend against border raids by the Scots, who will try to gain an advantage while England is distracted by an invasion of France. Canterbury tries to reassure him, but Henry continues to speak about the danger from Scotland, since the Scots always attack when the English are engaged in a war in France. Canterbury again tries to reassure him, saying that even when all the nobility was fighting in France, England was well able to defend itself, and even on one occasion captured the Scottish king. Taking up Henry's point, a lord warns that if the English invade France, the Scots will behave like the mouse when the cat is away, and cause havoc. Exeter, however, extends Canterbury's argument, which encourages the archbishop to clinch his case. He likens a well-ordered human society to a colony of bees, in which each bee has its appointed task and station, and all their diverse activities work together for the good of the colony. He therefore advises Henry to invade France with a quarter of his available man-power. The rest can stay at home and defend its borders.

Henry calls for the French ambassadors. Before they arrive, he announces his decision: he will invade and conquer France, since he is now convinced that the French throne rightfully belongs to him.

The ambassadors enter, bearing a message from the Dauphin. One of them carries a chest. Henry receives them graciously and allows the ambassador to speak. The ambassador brings an insulting message. The Dauphin alludes to Henry's reputation for being too fond of dancing and reveling, saying that there is nothing in France that can be won by such means. He sends Henry a gift, and requests to hear no more of his dynastic claims. 

Exeter opens the chest, to reveal the gift as tennis balls (an allusion to Henry's supposed preference for idling his time away in trivial pursuits).

Henry remains calm. He thanks the Dauphin for the gift. Using the language of tennis, he announces that he is going to take the throne of France. He explains that despite appearances to the contrary, in his wild youth he was in fact making good use of his time. And he warns the Dauphin that he will act like a King when he makes his claim on France. He will rise up with such glory that France will be dazzled. The Dauphin's joke with the tennis balls will rebound on him, for there will be much death and destruction in France because of it. Henry emphasizes that everything lies in the will of God, and he will come to France in God's name, for his cause is just. 

The ambassadors exit. Henry says that all his thoughts now focus on France. He tells the nobles to marshal all their forces, for with God's help they will beat the Dauphin.

Analysis

The scene shows the chronic habit of the French, which continues right up to the battle of Agincourt, of underestimating the English King. Henry reveals himself to be calm and resolute. He does not wish to proceed with his claim to the French throne unless it can be legally justified. He listens to the opinions of his advisers before making his decision, although it must be said that there is hardly much variety in the opinions presented to him. The young King is being urged to go to war in no uncertain terms, by men far more experienced than he, but he still gives the impression that the decision is his and his alone. Needless to say, the conniving churchmen do not come across in a favorable light. The archbishop's long speech is often played as comedy on the stage, although it seems unlikely that Shakespeare intended it this way.