Earl of Chester (1253)
'King of Sicily' (1255-1258)
1st Earl of Leicester (1265-1296)
1st Earl of Derby (1266-1296)
1st Earl of Lancaster (1267-1296)
Born 1245 Died 1296
Edmund was the second son of Henry III and Eleanor of Provence and therefore the younger brother of the 'Lord Edward', who later became king Edward I.
A number of sources show that Edmund was created Earl of Chester around the year 1253, but Henry III apparently had second thoughts and the earldom of was transferred to his elder brother in the following year. Henry had other plans for Edmund, and when he was ten years old he was formally invested as king of Sicily by Pope Alexander IV.1
That particular title therefore didn't amount to much (The Sicilians had other ideas and appointed their own king Conrad II), and Edmund was only ever king of Sicily in name only, and the grant was in any case withdrawn by the papacy in 12582. It did however involve his father Henry III in spending money that he did not have, which his barons were unwilling to give him and directly led to the Provisions of Oxford and the Barons War of 1264-1265.
Edmund himself played little part in these events that he'd indirectly inspired, other than he dutifully held Dover Castle until he was ordered to surrender it to the rebels by Henry III. But with the defeat and death of Simon de Montfort at the battle of Evesham that ended the Barons War, Edmund was to profit greatly from the distribution of lands seized from the defeated rebels.
Therefore in 1265, when Edmund had reached the age of twenty, he was given de Montfort's estates and earldom of Leicester (which came attached with the office of Steward of England). The very next year he benefited from the rebellion of Robert de Ferrers, the Earl of Derby, and was therefore created Earl of Derby and granted most of the de Ferrers lands, including the Honour of Lancaster. In 1267 Edmund was granted the entirely new earldom of Lancaster, and was afterwards generally known under the title of Earl of Lancaster effectively giving birth to what night be called the first house of Lancaster.
Between the years 1271 and 1272 he joined his elder brother, the Lord Edward on Crusade, and on his return he took to wearing the symbol of the cross on his back and was thereafter generally known as 'Edmund Crouchback'.
When his elder brother Edward became king on his return in 1272, Edmund became on of his brother's most faithful supporters, serving in Edward's various wars in both Wales (where he was active in the supression of the revolt of Rhys ap Maredudd in 1287) and Scotland, and was later involved with the negotiations with Philip the Fair, the king of France in the years 1293 to 1294, which ultimately failed as Philip pronounced that the king of England had forfeited Gascony.
Edward I appointed him as lieutenant of Gascony in early 1296, and he departed for France with the Earl of Lincoln where he laid siege to Bordeaux but he died on the 5th June that same year, supposedly of disappointment after failing to capture Bordeaux. His body was returned to England and interred at Westminster Abbey.3
He was married twice, firstly in 1272 to Aveline de Fortibus, the daughter of William de Fortibus, the Earl of Albemarle, but she died the following year. In 1275 he married for the second time to Blanche of Artois, the widow of Henry I, king of Navarre and a grand-daughter of Louis VIII, king of France, and through this marriage Edmund also assumed the title of Count Palatine of Champagne and Brie.
Edmund was forced to renounce this title in 1284 with the marriage of Blanche's daughter (by her first marriage), Jeanne to the aforementioned Philip the Fair, who at that time was merely the heir to the crown of France. But it was through this connection with Champagne, or more precisely the district of Provins that Edmund came to adopt the Damask rose of Provins as his personal emblem and hence the red rose of Lancaster.
As noted above, he became known as 'Edmund Crouchback' because of his habit of wearing a cross on the back of his tunic but the epithet of 'Crouchbank' was later misunderstood, and later gave rise to the belief that he was in some way physically deformed. In fact Henry IV sought to justify his usurpation by claiming that his ancestor Edmund Crouchback had actually been the eldest son of Henry III, but that he was overlooked in favour of his 'younger' brother the Lord Edward precisely because of this deformity. 4
There was no truth whatosever in this belief, but it remained the 'foundation' of the Lancastrian claim to the throne and part of the propoganda used to support Henry IV and his successors against the rival Yorkist claimants.
NOTES
1 The Papacy was playing power politics and wanted someone other than the Holy Roman Emperor to control the kingdom of Sicily; they got nowhere with Henry III in the end but eventually got Charles of Anjou to do the job.
2 Although it explains why Edmund has since sometime been known as Edmund of Sicily.
3 Where his tomb still survives virtually intact. See
http://www.kfki.hu/~arthp/html/zgothic/gothic/3/05e_1300.html
4 There is also an entry in the chronicle of Adam of Usk which states that "they declared that the same Edmund was the eldest son of King Henry III, but that on account of his mental weakness, his birthright had been set aside and his younger brother, Edward, preferred in his place."
SOURCES
The 1911 Encyclopedia Brittanica entry for EDMUND OF SICILY
See http://1911encyclopedia.org/index.htm
Charles Arnold Baker The Companion to British History (Longcross Press, 1996)
Edmund Plantagenet, Earl of Lancaster and his descendants
http://www.maximiliangenealogy.co.uk/burke1/Burkeindex.htm
which reproduces Burkes Peerage Vol 1 1851
Heritage Sites in Europe; France; Provins, Seine-et-Marne, Paris-Ile-de-France
http://www.heritagesites.eu.com/france/provins.htm