Duke of Lancaster

The dukedom of Lancaster is a former English peerage, created three times in the Middle Ages, which finally merged in the Crown when Henry V succeeded to the throne in 1413. Despite the extinction of the dukedom the title has continued to be used to refer to the reigning monarch of the United Kingdom in relation to the County Palatine of Lancaster and the Duchy of Lancaster, an estate held separately from the Crown Estate for the benefit of the sovereign.

History
There were three creations of the dukedom of Lancaster during the fourteenth and fifteenth centuries. The first creation was on 6 March 1351 for Henry of Grosmont, 4th Earl of Lancaster, a great-grandson of Henry III; he was also 4th Earl of Leicester, 1st Earl of Derby, 1st Earl of Lincoln and Lord of Bowland. When he died in 1361 the peerage became extinct.

The second creation was on 13 November 1362, for John of Gaunt, 1st Earl of Richmond and third surviving son of King Edward III. He became Henry of Grosmont's son-in-law through his marriage to Blanche of Lancaster, Henry's second daughter and eventual heir. When Gaunt died on 4 February 1399 the dukedom passed to his son, Henry of Bolingbroke, 1st duke of Hereford. Later that same year Bolingbroke usurped the throne of England from Richard II, becoming Henry IV, at which point the dukedom merged in the Crown.

Henry re-created the dukedom on 10 November 1399 for his eldest son Henry of Monmouth, Prince of Wales. In 1413 Monmouth ascended the throne as King Henry V and the dukedom merged in the crown again, where it has remained ever since.

Nevertheless, the title continues to be used to refer to the monarch in relation to Lancashire and the Duchy of Lancaster, the estate associated with the former dukedom. It was customary at formal dinners in the historic county boundaries of Lancashire and in Lancastrian regiments of the armed forces for the Loyal Toast to be announced as "The King, Duke of Lancaster". In addition, in Lancaster it is still common to hear the national anthem sung as "God save our gracious King, long live our noble Duke". However, the legal basis for the sovereign to use the title has been disputed as the right to inheritance of the title only arises upon each creation, which is different than the crown's right to the duchy's estate after the merger. In particular, George V was given legal advice that it was “extremely unlikely” that he was the duke of Lancaster.

First creation, 1351–1361
House of Plantagenet also Earl of Derby (1337), Earl of Leicester (1345), Earl of Lancaster (1345), Earl of Lincoln (1349), Earl of Moray (1359), Lord of Beaufort and Nogent (1345) Grosmont Castle son of Henry, 3rd Earl of Lancaster and Maud Chaworth|| Isabel of Beaumont c. 1337 2 children Leicester Castle aged 50–51
 * Henry of Grosmont
 * [[File:Portrait of Henry, Duke of Lancaster - William Bruges's Garter Book (c.1440-1450), f.8 - BL Stowe MS 594 (cropped).jpg|100px|Henry of Grosmont]] || c. 1310
 * 23 March 1361
 * colspan="5" | Henry of Grosmont died in 1361 without male issue.
 * }
 * }

Second creation, 1362–1399
House of Lancaster (founder) also Duke of Aquitaine (1390), Earl of Richmond (1342–1372), Earl of Leicester, Earl of Lancaster, Earl of Derby, Baron of Halton (1361) Ghent son of Edward III and Philippa of Hainault|| Blanche of Lancaster 19 May 1359 – 12 September 1368 8 children Constance of Castile 21 September 1371 – 24 March 1394 2 children Katherine Swynford 13 January 1396 4 children Leicester Castle aged 58 House of Lancaster also Duke of Hereford (1397), Earl of Northampton (1337) Bolingbroke Castle son of John of Gaunt and Blanche of Lancaster c. 1381 – 4 June 1394 6 children Joan of Navarre 7 February 1403 no children Westminster aged 46
 * John of Gaunt
 * Johnofgaunt.jpg
 * 6 March 1340
 * 3 February 1399
 * Henry Bolingbroke
 * Henry Bolingbroke
 * Illumination of Henry IV (cropped).jpg
 * c. April 1367
 * Mary de Bohun
 * 20 March 1413
 * colspan=5 | Henry Bolingbroke seized the throne as Henry IV in 1399, and all of his titles merged with the crown.
 * }
 * }

Third creation, 1399–1413
House of Lancaster also Prince of Wales and Earl of Chester (1399), Duke of Cornwall (1337), Duke of Aquitaine (1390) Monmouth Castle son of Henry IV and Mary de Bohun|| Catherine of Valois 2 June 1420 1 child Château de Vincennes aged 35
 * Henry of Monmouth
 * Henry5.JPG
 * 16 September 1386
 * 31 August 1422
 * colspan=5 | Henry of Monmouth succeeded to the throne as Henry V in 1413, and his titles merged with the crown.
 * }
 * }