Sir Isumbras is a medieval metrical romance written in Middle English and found in no fewer than nine manuscripts dating to the fifteenth century. This popular romance must have been circulating in England before 1320, because William of Nassington, in his work Speculum Vitae, which dates from this time, mentions feats of arms and other 'vanities', such as those found in stories of Sir Guy of Warwick, Bevis of Hampton, Octavian and Sir Isumbras. Unlike the other three stories, the Middle English Sir Isumbras is not a translation of an Old French original.
Sir Isumbras is a proud knight who is offered the choice of happiness in his youth or his old age. He chooses the latter, and falls from his high estate by the will of Providence. He is severely stricken; his possessions, his children and, lastly, his wife, are taken away; and he himself becomes a wanderer. After much privation he trains as a blacksmith, learning to forge anew his armour, and he rides into battle against a sultan. Later, he arrives at the court of the sultan's queen, who proves to be his long-lost wife. He attempts to Christianise the Islamic lands over which he now rules, provoking a rebellion which is then defeated when his children miraculously return to turn the tide of battle.
Sir Isumbras is a relatively short Middle English romance, less than eight hundred lines in length, in twelve-line tail-rhyme stanzas. This the form of romance is parodied by Geoffrey Chaucer in his Canterbury Tale of Sir Thopas. Tail-rhyme verse, however, was very popular in late-medieval English for recording tales of adventure and romance, and used in many Middle English romances, such as Emaré,Sir Amadace,Sir Gawain and the Carle of Carlisle,Ipomadon and Sir Gowther. A typical verse begins with a group of three lines, such as this one describing the scene as Sir Isumbras arrives at his burnt-out manor, during his long slide into penuary and loss: