The Archbishop of Canterbury, worried over impending legislation that would effectively rob the Church in England of its power and wealth, convinces King Henry V to forego this pursuit in favor of laying claim to France. Armed with a legal technicality, Henry plans to take the throne of France by whatever means necessary. The Dauphins insulting response-sending an ambassador with a gift of tennis balls - convinces Henry that the French will only respond to war. He arranges for an army to invade France. However, since he needs to leave behind enough troops to guard the country while hes away, to quell any potential uprising, Henry is left with a relatively small invasion force.
In fact, Henry must deal with one plot before even crossing the Channel. Lords Cambridge, Scroop, and Grey are discovered to be conspiring to assassinate Henry (paid for by the French). Henry makes a very public example of all three, arresting them in person and seeing to their execution. The army then lays siege to Harfleur and captures it. Henry attempts to take his army out of France before the onset of winter; however, now the French are certain that they can teach the young king a humiliating lesson on the field of battle. Henry is resolute, nonetheless. If the French want a battle, they will have it.
While in camp, Henry disguises himself as a common soldier in order to mingle with his troops before the battle. There he talks candidly with his men, and they with him. The men may be leery of their kings motives for the war, but their willingness to battle the French army is undaunted. The next day at Agincourt, Henry makes the stirring St. Crispins Day speech, spurring his men on with thoughts of glory even though he knows his army is outnumbered five to one. Aided mightily by the longbows of his archers, Henry makes the day a rout leaving 10,000 French dead and only 27 English. The French must now sue for peace, which Henry will grant - completely on his own terms, of course. According to the terms of the treaty, Henry will marry Princess Katherine of France and will be named as heir to the French throne. England and France will thus be united in peace.