From October 1400 the administration of Wales was conducted in his name; less than three years later he was in actual command of the English forces and fought against Harry Hotspur at Shrewsbury. It was there, in 1403, that the sixteen-year-old prince was almost killed by an arrow which lodged itself in his face. An ordinary soldier would have been left to die from such a wound, but Hal had the benefit of the best possible care, and, over a period of several days after the incident, the royal physician crafted a special tool in order to extract the tip of the arrow without doing further damage. The operation was successful, and probably gave the prince permanent scars which would have served as a testimony to his experience in battle.
The Welsh revolt of Owen Glendower absorbed Hal's energies till 1408. Then, as a result of the king's ill-health, he began to take a wider share in politics. From January 1410, helped by his uncles Henry and Thomas Beaufort - legitimised sons of John of Gaunt - he had practical control of the government.
Both in foreign and domestic policy he differed from the king, who in November 1411 discharged the Prince from the council. The quarrel of father and son was political only, though it is probable that the Beauforts had discussed the abdication of Henry IV, and their opponents certainly endeavoured to defame the prince. It may be to that political enmity the tradition of Henry's riotous youth, immortalized by Shakespeare, is partly due. Henry's record of involvement in war and politics, even in his youth, disproves this tradition. The most famous incident, his quarrel with the chief justice, has no contemporary authority and was first related by Sir Thomas Elyot in 1531.
The story of Falstaff originated partly in Henry's early friendship for Sir John Oldcastle. That friendship, and the prince's political opposition to Thomas Arundel, Archbishop of Canterbury, perhaps encouraged Lollard hopes. If so, their disappointment may account for the statements of ecclesiastical writers, like Thomas Walsingham, that Henry on becoming king was changed suddenly into a new man.
Henry could now turn his attention to foreign affairs. A writer of the next generation was the first to allege that Henry was encouraged by ecclesiastical statesmen to enter into the French war as a means of diverting attention from home troubles. For this story there is no foundation. The restoration of domestic peace was the king's first concern, and until it was assured he could not embark on any wider enterprise abroad. Nor was that enterprise one of idle conquest. Old commercial disputes and the support which the French had lent to Glendower was used as an excuse for war, whilst the disordered state of France afforded no security for peace. Henry may have regarded the assertion of his own claims as part of his kingly duty, but in any case a permanent settlement of the national quarrel was essential to the success of his world policy. The campaign of 1415, with its brilliant conclusion at Agincourt (October 25), was only the first step. Two years of patient preparation followed.
The command of the sea was secured by driving the Genoese allies of the French out of the Channel. A successful diplomacy detached the emperor Sigismund from France, and by the Treaty of Canterbury paved the way to end the schism in the Church. So in 1417 the war was renewed on a larger scale. Lower Normandy was quickly conquered, Rouen cut off from Paris and besieged. The French were paralysed by the disputes of Burgundians and Armagnacs. Henry skilfully played them off one against the other, without relaxing his warlike energy. In January 1419 Rouen fell. By August the English were outside the walls of Paris. The intrigues of the French parties culminated in the assassination of John of Burgundy by the dauphin's partisans at Montereau (September 10, 1419). Philip, the new duke, and the French court threw themselves into Henry's arms. After six months' negotiation Henry was by the Treaty of Troyes recognized as heir and regent of France, and on the June 2, 1420 married Catherine, the king's daughter. Following his death, Catherine of Valois would secretly marry a Welsh courtier, Owen Tudor, grandfather of King Henry VII of England.
Henry V was now at the height of his power. His eventual success in France seemed certain. He shared with Sigismund the credit of having ended the Great Schism by obtaining the election of Pope Martin V. All the states of western Europe were being brought within the web of his diplomacy.
The headship of Christendom was in his grasp, and schemes for a new Crusade began to take shape. He actually sent an envoy to collect information in the East; but his plans were cut short by death. A visit to England in 1421 was interrupted by the defeat of Clarence at Baugé. The hardships of the longer winter siege of Meaux broke down his health, and he died of dysentery at Bois de Vincennes on August 31, 1422. Had he lived another two months, he would have been crowned King of France.
Henry's last words supposedly expressed a wish that he might live to rebuild the walls of Jerusalem. This ideal was founded consciously on the model of King Arthur, a model which was becoming outdated. Yet Henry was not reactionary. His policy was:
"His dazzling achievements as a general have obscured his more sober qualities as a ruler, and even the sound strategy, with which he aimed to be master of the narrow seas. If he was not the founder of the English navy he was one of the first to realize its true importance. Henry had so high a sense of his own rights that he was merciless to disloyalty. But he was scrupulous of the rights of others, and it was his eager desire to further the cause of justice that impressed his French contemporaries. He has been charged with cruelty as a religious persecutor; but in fact he had as prince opposed the harsh policy of Archbishop Thomas Arundel, and as king sanctioned a more moderate course. Lollard executions during his reign had more often a political than a religious reason. To be just with sternness was in his eyes a duty. So in his warfare, though he kept strict discipline and allowed no wanton violence, he treated severely all who had in his opinion transgressed. In his personal conduct he was chaste, temperate and sincerely pious. He delighted in sport and all manly exercises. At the same time he was cultured, with a taste for literature, art and music." This is now regarded as a rather old-fashioned and prejudiced view of Henry's reign.
Henry lies buried in Westminster Abbey. His tomb was stripped of its splendid adornment during the Reformation. The shield, helmet and saddle, which formed part of the original funeral equipment, still hang above it. The head has now been replaced.
He was succeeded by his infant son, Henry VI.