Fastolfe could be seen as a kind of forerunner for Falstaff, though we know Falstaff is in fact based on Sir John Oldcastle. Fastolfe is in fact a historical figure. Shakespeare’s Fastolfe displays cowardliness in the face of danger, and is punished for his actions in front of the king.
The following information is quoted from the Oxford Dictionary of National Biography, written by G. L. Harriss.
Fastolf, Sir John (1380–1459), soldier and landowner, was born into a minor gentry family in Norfolk and in early manhood served under the duke of Clarence in Ireland. His marriage there, on 13 January 1409, to Millicent, daughter of Robert, Lord Tiptoft (d. 1372), and widow of Sir Stephen Scrope, decisively improved his fortunes, bringing him lands to the value of £240 p.a. He served under Clarence in Aquitaine in 1412–13 as deputy constable of Bordeaux and remained there as captain of Soubise and Veyres in 1413–14. On his return Fastolf joined Henry V's expedition in 1415 and fought at Agincourt, but returned to Harfleur early in 1416 as a knight under the duke of Exeter, and participated in the battle of Valmont and the close siege of the town by the French. It was with Clarence and Exeter that he served from 1417 to 1421: present at the sieges of Caen and Rouen, he held the captaincies of Harfleur and Fécamp, and was granted in tail male four lordships in the bailliage of Caux in January 1419.
During Henry V's absence in England, the duke of Exeter, as governor of Paris, made Fastolf captain of the Bastille de St Antoine which he defended during the disturbances after the battle of Baugé in 1421. Following Henry V's death and Exeter's return to England he, with other professional captains, formed a group under the command of the regent, John, duke of Bedford, which carried forward the momentum of the conquest. Appointed lieutenant in Normandy for a year in 1422, Fastolf was employed in clearing the region to the south-west of Paris, and held captaincies at Fresnay-le-Vicomte and Alençon. He distinguished himself in Bedford's victory over the Dauphinist–Scottish force at Verneuil in August and was made a knight-banneret in 1424 and knight of the Garter in 1426. From the ransoms of his prisoners at this battle, who included the duke of Alençon, he claimed to have gained 20,000 marks, although he in fact realized only part of this sum. He and Lord Scales then pressed ahead with the reduction of Maine and capture of Le Mans, of which he was made governor until the autumn of 1427. His own fiefs in the area included the castle of Sillé-le-Guillaume from which he took the title of baron. Bedford's confidence in Fastolf, both as a military commander and as chief steward of his household and member of the grand conseil from 1422 to 1435, was reciprocated by Fastolf's respect for the duke's policy and judgement. If he shared Bedford's mistrust of the siege of Orléans he in no way held aloof from it. In February 1429, while bringing supplies for the siege from Paris, he won the ‘battle of the herrings’, at Rouvray, by using barrels of the fish as a stockade. Four months later, however, retreating with Lord Talbot and Lord Scales from Beaugency, the rearguard was overwhelmed at Patay and only the van, under Fastolf, evaded death or capture by a rapid withdrawal. Talbot, made prisoner, later charged Fastolf with cowardice and demanded his removal from the Order of the Garter. The case against him was still being heard in the 1440s and, although he was vindicated, Fastolf's reputation was tainted; his enemies' taunt of being ‘chevalier fuytif’ (‘a cowardly knight’) , though undeserved, was particularly wounding to one who sought chivalric renown. Bedford's trust in him seems not to have wavered. Fastolf continued to be given captaincies: of Honfleur (1424–34), Verneuil (1429), and Caen (1430–37), and field commands with Lord Willoughby in 1431.
As governor of Bedford's household Fastolf accompanied him to England in 1433–4, but the year 1435 brought traumatic losses. Bedford's death in September was quickly followed by the rising in the Pays de Caux where some of Fastolf's prime estates lay; their yield of over £600 p.a. was reduced by one-third. As well as a soldier he had become a landowner of substance in France. He employed an attorney in the parlement—Maître Jean de Paris—to pursue his claims over land, ransoms, and jurisdictions. His receiver, Thomas Overton, accused him of oppressing the people of Alençon. But this second crisis in English fortunes, with Normandy itself exposed to attack, prompted him to start disengaging. Although he responded by urging an aggressive strategy—the creation of a scorched earth zone along the borders of Normandy by ‘sharpe and cruelle war’ (Stevenson, 580)—and deplored the policy of piecemeal defence, his own days of soldiering were finished. As one of Bedford's three executors for his French estate Fastolf was mainly engaged during the next four years in disposing of the duke's effects, constructing his tomb, and fulfilling his bequests. His obligations to the duke's creditors continued for the rest of his life, as did his own obsession with recovering the sums owed to himself for ransoms and wages.
For ten years after 1426 Fastolf had periodically remitted to England large sums from his profits of war for the purchase of land, mainly in Norfolk. When he returned in 1439 he acquired the Boar's Head tavern in Southwark where he also built himself a residence. At Caister, Norfolk, his fine moated castle was completed and furnished by 1448. In all he had spent £13,885 in purchasing property and another £9495 on improving it. In 1445 the annual value of his English lands was £1061, that of his French lands £401. His houses were furnished to baronial standards, his liquid wealth enabled him to lend and invest on a commercial scale, and among his jewels was a collar of the White Rose valued at 4000 marks that had belonged to the duke of York. Fastolf returned to England in 1439 rich, honoured, well connected, and in full mental and physical vigour, but instead of the respect, recognition, and ease that he anticipated he experienced twenty years of hostility and persecution that almost brought his ruin. His fortunes were caught up in the contentions of domestic politics not because he was actively involved in them, but because his background linked him to the opponents of the government and his lack of an heir attracted the covetous and unscrupulous.
Fastolf's long years of war had inculcated distrust and contempt of the French which made him a natural critic of the peace policy of William de la Pole, duke of Suffolk. He was later to denounce the ‘dissimuled’ truce of Tours (Boke of Noblesse, 41) and in 1448 urged Edmund Beaufort, duke of Somerset, to restock the castles of Normandy, safeguard the sea lanes, choose reliable captains, and win the loyalty of the Normans. He had already seen his fiefs in Maine surrendered without obtaining compensation, and by 1450 when all but Caen and Harfleur had gone he was still vainly urging the dispatch of a powerful army to hold them. The anger and shame Fastolf felt at the English collapse still burnt fiercely in 1451–2 when his secretary William Worcester put his master's views on record in the Boke of Noblesse, namely that Normandy had been lost through French trickery and the English corruption and indiscipline that followed Bedford's death. Believing that God and justice upheld the English, he affirmed that Normandy could and would be recovered.
Not merely Fastolf's views but his associations were suspected by the duke of Suffolk and the court. He had been the counsellor of both Humphrey, duke of Gloucester, and Richard, duke of York, and the critic of Somerset. He was the neighbour and friend of John Paston, an opponent of the court affinity in Norfolk now led by the duke of Suffolk. From 1447 Suffolk and members of the court raided and seized Fastolf's lands, harassed his tenants, and bent the law to dispossess him. With the fall of Suffolk in 1450 Fastolf, in association with John Paston and Justice Yelverton, sought the backing of the dukes of York and Norfolk to obtain redress, a hope which faded as Somerset established his power in 1451 and Fastolf found himself delated for treason and narrowly escaped forfeiture. Throughout the 1450s, with his fortune vulnerable to national politics, his plans for a college of priests at Caister impeded, his claims for wages and ransoms still unsettled, he was increasingly distrustful of those who had eyes on his wealth and became the ‘close fisted, litigous, and irascible old man’ revealed in the Paston letters from this decade (McFarlane, 176). Yet he never resorted to force in his defence, he prided himself on keeping faith with his superiors and subordinates, and claimed to stand for the defence of property and the common good in his neighbourhood. Not until the very last, after redrafting his will many times, did he, by a nuncupative act which John Paston could alone attest, bestow all his properties on Paston for the foundation of his college. Fastolf died on 5 November 1459 just as the civil war began in earnest, and not until 1470, after years of bitter wrangling and the loss of many of his lands, was the residue awarded to Magdalen College, Oxford, in place of the college at Caister. He was buried in the chapel at the abbey of St Benet of Hulme which he had built, but of that nothing survives. As well as a fine soldier and military theorist, and a shrewd and grasping man of business, he was a literary patron whose two amanuenses, William Worcester and Stephen Scrope, produced at his instigation the one a biography of his master, now lost, the other translations in English of De senectute and Christine de Pisan's Épître d'Othéa.
Although Shakespeare adapted Fastolf's name for his character Sir John Falstaff, the personality he gave him was wholly imaginary. In the original draft of Henry IV (1597) the companion of Prince Hal was the historically correct Sir John Oldcastle (d. 1417), who had also figured in the Famous Victories of Henry V (1594). Apparently to meet the objection of Oldcastle's descendant, Lord Cobham, Shakespeare changed the name to Falstaff, doubtless suggested by the fact that Fastolf had owned the Boar's Head tavern in Southwark. Shakespeare introduced the character of Oldcastle–Falstaff to emphasize Henry V's conversion on his accession from a life of riot and dissipation. The corpulent, cowardly, and mendacious Falstaff was the opposite of the austere and dedicated king who historically had repudiated his former companion Oldcastle on account of his Lollard beliefs. Fastolf himself was neither self-indulgent nor heterodox and was never among Henry's close friends. Falstaff's rumbustious and endearing character quickly took on a life of its own, becoming not merely the inspiration for The Merry Wives of Windsor but the subject of numerous musical adaptations, culminating in Verdi's Falstaff (1893) and Vaughan Williams's Sir John in Love (1935), and in the film Chimes at Midnight (1966), in which the director, Orson Welles, himself played Falstaff.