Famed for her beauty and charm, she was also a great heiress. In 
          1349 her marriage of 1340 to William de Montacute, 5th Earl of 
          Salisbury, was set aside because of a precontract in 1339 with Sir 
          Thomas Holand. Joan and Sir Thomas became the parents of five children
          and, after the death of Sir Thomas, she married her cousin, Edward, 
          Prince of Wales, and they became the parents of two sons, Edward, who 
          died aged about seven, and the future King Richard II. 
              From 1362 to 1371 she lived with the Prince of Wales in Gascony, 
          where both sons were born. After the death of the Prince of Wales, she
          returned to England. There she protected John of Gaunt from Londoners 
          who rioted against his support for John Wycliffe. Although 'devoted to
          pleasure, and so fat from eating that she could scarcely walk' 
          according to the chronicler Thomas Walsingham, Joan mediated between 
          her son, King Richard II, and John of Gaunt when they quarrelled in 
          1385. On 7 August 1385 she died at Wallingford Castle, in Berkshire. 
 

Source: Leo van de Pas