A famous knight and war hero became the first Duke of Lancaster.

The warrior Duke

Henry Grosmont succeeded his father Henry, 3rd Earl of Lancaster, to the Lancastrian earldom in 1345. One of the most celebrated noblemen of his day, Henry was also a diplomat, administrator and soldier who took part in many of Edward III's military campaigns. 

To reward him for his chivalric achievements in France, on 6 March 1351 Edward III created Henry 1st Duke of Lancaster "in recognition of astonishing deeds of prowess and feats of arms". 

Lancashire, County Palatine

In the same charter, Edward III raised Lancaster to a County Palatine for Henry's lifetime. This meant that the new Duke had sovereign rights in the county in the spheres of justice and administration. The law courts in Lancashire were under the Duke's administration, and he appointed the sheriff, judges, justices of the peace and other senior officials. 

In medieval England, Palatnate powers were devolved royal powers, for use in regions where central government was difficult. The creation of Lancashire as a County Palatine may have been intended by Edward III as a protective barrier against the Scots.

"John of Gaunt, time honoured Lancaster"

Henry, 1st Duke of Lancaster died at Leicester Castle in 1361 without a male heir. The ducal title became extinct, and the palatinate powers reverted to King Edward III. The inheritance passed to Henry's daughters, Blanche and Maude. Lancaster was part of Blanche's dowry when she married King Edward III's son, John of Gaunt, in 1359. Maude died without children in 1362, and her portion of the inheritance passed to her sister Blanche, reuniting the inheritance.

John of Gaunt, a very powerful man,  was created 2nd Duke of Lancaster by Edward III in 1362. John recovered many of the Lancaster possessions that had been lost in 1322. He also made valuable additions to the Duchy, including the Honors of Tickhill, Knaresborough, Pevensey and High Peak, which he received in exchange for surrendering the Earldom of Richmond in North Yorkshire to his father in 1372.

On 28 February 1377, Edward III recreated the Palatinate for John's lifetime. In 1390, this grant was extended to include John's heirs. The Duke of Lancaster had become one of the most important figures in the country.