Edmund Crouchback in the context of "Earl of Leicester"

Henry III (1 October 1207 – 16 November 1272), also known as Henry of Winchester, was King of England, Lord of Ireland and Duke of Aquitaine from 1216 until his death in 1272. The son of John, King of England, and Isabella of Angoulême, Henry acceded to the throne when he was only nine in the middle of the First Barons' War. Cardinal Guala Bicchieri declared the war against the rebel barons to be a religious crusade and Henry's forces, led by William Marshal, defeated the rebels at the battles of Lincoln and Sandwich in 1217. Henry promised to abide by the Great Charter of 1225, a later version of Magna Carta (1215), which limited royal power and protected the rights of the major barons. Henry's early reign was dominated first by William Marshal, and after his death in 1219 by the magnate Hubert de Burgh, Earl of Kent. In 1230 the King attempted to reconquer the provinces of France that had once belonged to his father, but the invasion was a debacle. A revolt led by William Marshal's son Richard broke out in 1232, ending in a peace settlement negotiated by the Catholic Church.

Following the revolt, Henry ruled England personally, rather than governing through senior ministers. He travelled less than previous monarchs, investing heavily in a handful of his favourite palaces and castles. He married Eleanor of Provence, with whom he had five children. Henry was known for his piety, holding lavish religious ceremonies and giving generously to charities; the King was particularly devoted to the figure of Edward the Confessor, whom he adopted as his patron saint. He extracted huge sums of money from the Jews in England, ultimately crippling their ability to do business. As attitudes towards the Jews hardened, he later introduced the Statute of Jewry, which attempted to segregate the Jewish community from the English populace. In a fresh attempt to reclaim his family's lands in France, he invaded Poitou in 1242, leading to the disastrous Battle of Taillebourg. After this, Henry relied on diplomacy, cultivating an alliance with Frederick II, Holy Roman Emperor. Henry supported his brother Richard of Cornwall in his successful bid to become King of the Romans in 1256, but was unable to place his own son Edmund Crouchback on the throne of Sicily, despite investing large amounts of money. He planned to go on crusade to the Levant, but was prevented from doing so by rebellions in Gascony.

The House of Lancaster was a cadet branch of the royal House of Plantagenet. The first house was created when King Henry III of England created the Earldom of Lancaster—from which the house was named—for his second son Edmund Crouchback in 1267. Edmund had already been created Earl of Leicester in 1265 and was granted the lands and privileges of Simon de Montfort, 6th Earl of Leicester, after de Montfort's death and attainder at the end of the Second Barons' War. When Edmund's son Thomas, 2nd Earl of Lancaster, inherited his father-in-law's estates and title of Earl of Lincoln he became at a stroke the most powerful nobleman in England, with lands throughout the kingdom and the ability to raise vast private armies to wield power at national and local levels. This brought him—and Henry, his younger brother—into conflict with their cousin King Edward II, leading to Thomas's execution. Henry inherited Thomas's titles and he and his son, who was also called Henry, gave loyal service to Edward's son King Edward III.

The second house of Lancaster was descended from John of Gaunt, a Plantagenet prince, who married the heiress of the first house, Blanche of Lancaster. Edward III married all his sons to wealthy English heiresses rather than following his predecessors' practice of finding continental political marriages for royal princes. Henry of Grosmont, 1st Duke of Lancaster, had no male heir so Edward married his son John to Henry's heiress daughter and John's third cousin Blanche of Lancaster. This gave John the vast wealth of the House of Lancaster. Their son Henry usurped the throne in 1399, creating one of the factions in the Wars of the Roses. There was an intermittent dynastic struggle between the descendants of Edward III. In these wars, the term "Lancastrian" became a reference to members of the family and their supporters. The family provided England with three kings: Henry IV (r. 1399–1413), Henry V (r. 1413–1422), and Henry VI (r. 1422–1461 and 1470–1471).

The Honour of Lancaster was a medieval English honour (a large feudal lordship containing several different fiefs), located primarily in the north-west of England. It began as the fief granted by William the Conqueror to Roger the Poitevin after the Norman conquest in 1066. This included the lands between the River Ribble and the River Mersey, as well as the district of Amounderness, north of the Ribble.

After Roger lost his English lands the honour was given to various members of the royal family and eventually came into the hands of Edmund Crouchback, who was a son of King Henry III. It remained the possession of his heirs until one of them, Henry Bolingbroke, became king of England as Henry IV. Since then the honour has been a possession of the ruling monarch.

The "Sicilian business" is a historiographical term used to describe the failed attempt by Henry III of England to claim the Kingdom of Sicily for his son Edmund, who had been offered the throne by the papacy. Sicily, established in the twelfth century as a theoretical papal fief, had been ruled by Holy Roman Emperor Frederick II from 1198 until his death in 1250; Pope Innocent IV now sought to install an agreeable sovereign to succeed his longtime adversary. After failed negotiations with Edmund's uncles Richard of Cornwall and Charles of Anjou, the papacy formally offered the throne to the English prince in 1254. For the project, Henry III was tasked with delivering Edmund and armed forces to Sicily to claim it from Manfred, who was serving as regent for Frederick II's grandson Conradin; the papacy was to offer assistance.

A strategic marriage was planned for Edmund; potential brides were the dowager queen of Cyprus or a daughter of Manfred in order to resolve the dispute over the kingdom. Neither union came to fruition, and despite continued attempts to secure support and financing, Henry III's efforts to establish Edmund as the Sicilian monarch faced numerous setbacks. Pope Alexander IV, who had succeeded Innocent IV in 1254, was no longer in a position to effectively finance the project, demanding payment from Henry III as compensation for the papacy's contributions to the campaign. Finding only minimal support from Parliament and faced with the threat of excommunication from Rome, Henry III resorted to extorting money from his domestic clergy in an attempt to pay the debts. The "Sicilian business" became entangled with broader political troubles in England, and the project ultimately collapsed. Pope Urban IV formally revoked the grant of the Kingdom of Sicily to Edmund in 1263 and instead consigned it to Charles of Anjou, who successfully assumed control of the kingdom in 1266.

The title of Earl of Lancaster was created in the Peerage of England in 1267. It was succeeded by the title Duke of Lancaster in 1351, which expired in 1361. (The most recent creation of the ducal title merged with the Crown in 1413.)

King Henry III of England created the Earldom of Lancaster—from which the royal house of Henry IV was named—for his second son, Edmund Crouchback, in 1267. Edmund had already been created Earl of Leicester in 1265 and following the Second Barons' War and the death and attainder of the king's rebellious brother-in-law Simon de Montfort, 6th Earl of Leicester in 1265, the latter's lands, including most notably Kenilworth Castle in Warwickshire, had been awarded to him.