Question: In what battle did Richard Plantagenet's claimed father die?

Context paragraphs:
Richard III of England: Richard III (2 October 1452 – 22 August 1485) was King of England from 1483 until his death in 1485, at the age of 32, in the Battle of Bosworth Field.  He was the last king of the House of York and the last of the Plantagenet dynasty.  His defeat at Bosworth Field, the last decisive battle of the Wars of the Roses, marked the end of the Middle Ages in England.  He is the subject of the historical play "Richard III" by William Shakespeare.

Thomas St. Leger: Sir Thomas St Leger (c. 1440 – executed 8 November 1483) was the second son of Sir John St Leger (d.1441) of Ulcombe, Kent, and his wife, Margery Donnet.  He was also the second husband of Anne of York (10 August 1439 – 14 January 1476), daughter of Richard Plantagenet, 3rd Duke of York (by his wife Cecily Neville) and thus she was an elder sister of Kings Edward IV (1461-1483) and Richard III (1483-1485).  His younger brother, Sir James St Leger of Annery in Devon, married Anne Butler, daughter of Thomas Butler, 7th Earl of Ormond, and was therefore an uncle to Thomas Boleyn, 1st Earl of Wiltshire.

Isabel of Cambridge, Countess of Essex: Isabel of Cambridge, Countess of Essex (1409 – 2 October 1484) was the only daughter of Richard, 3rd Earl of Cambridge and Anne Mortimer.  She was the sister of Richard Plantagenet, 3rd Duke of York, and like him a great-grandchild of Edward III of England.

Thomas Tresham (speaker): Sir Thomas Tresham (died 6 May 1471) was a British politician, soldier and administrator.  He was the son of Sir William Tresham and his wife Isabel de Vaux, daughter of Sir William Vaux of Harrowden.  Thomas's early advancement was due to his father's influence.  In 1443 he and his father were appointed as stewards to the Duchy of Lancaster's estates in Northamptonshire, Buckinghamshire, Bedfordshire and Huntingdonshire, and by 1446 Thomas was serving as an esquire for Henry VI, being made an usher of the king's chamber in 1455.  He was appointed a Justice of the Peace for Huntingdonshire in 1446, a position he held until 1459, and was returned to Parliament for Buckinghamshire in 1447 and Huntingdonshire in 1449.  Despite the Tresham family's close links with the royal court they were also on good terms with Richard Plantagenet, 3rd Duke of York, and when he returned from Ireland in 1450 Tresham and his father went to greet him.  Shortly after leaving home on 23 September they were attacked by a group of men involved in a property dispute with his father; William Tresham was killed, and Thomas was injured.

George Plantagenet, 1st Duke of Clarence: George Plantagenet, 1st Duke of Clarence, 1st Earl of Salisbury, 1st Earl of Warwick (21 October 144918 February 1478) was the third surviving son of Richard Plantagenet, 3rd Duke of York, and Cecily Neville, and the brother of English Kings Edward IV and Richard III.  He played an important role in the dynastic struggle between rival factions of the Plantagenets known as the Wars of the Roses.

Richard Plantagenet (Richard of Eastwell): Richard Plantagenet or Richard of Eastwell (?  1469 – 22 December 1550) was a reclusive bricklayer who was claimed to be a son of Richard III, the last Plantagenet King of England.

Richard of Conisburgh, 3rd Earl of Cambridge: Richard of Conisburgh, 3rd Earl of Cambridge (c. 20 July 1375 – 5 August 1415) was the second son of Edmund of Langley, 1st Duke of York, and Isabella of Castile.  At the age of forty, he was beheaded for his part in the Southampton Plot, a conspiracy against King Henry V.  He was the father of Richard Plantagenet, 3rd Duke of York, and the grandfather of King Edward IV and King Richard III.

Anne of York, Duchess of Exeter: Anne of York, Duchess of Exeter (10 August 1439 – 14 January 1476) was the first child and eldest surviving daughter of Richard Plantagenet, 3rd Duke of York, and Cecily Neville.  She was thus the eldest sister of Kings Edward IV (1461–1483) and Richard III (1483–1485); and of Edmund, Earl of Rutland, Elizabeth of York, Duchess of Suffolk, Margaret, Duchess of Burgundy and of George Plantagenet, 1st Duke of Clarence.

Edmund Beaufort, 2nd Duke of Somerset: Edmund Beaufort, 2nd Duke of Somerset, KG (1406 – 22 May 1455), sometimes styled 1st Duke of Somerset, was an English nobleman and an important figure in the Wars of the Roses and in the Hundred Years' War.  He also succeeded in the title of 4th Earl of Somerset and was created 1st Earl of Dorset and 1st Marquess of Dorset (previously held by his father and later forfeited), and Count of Mortain.  He was known for his deadly rivalry with Richard Plantagenet, 3rd Duke of York.

Edmund, Earl of Rutland: Edmund, Earl of Rutland (17 May 1443 – 30 December 1460) was the fifth child and second surviving son of Richard Plantagenet, 3rd Duke of York, and Cecily Neville.  He was born in Rouen.  At the time Rouen was the capital of English occupied France and his father held the office of Lieutenant of France.  He was killed at the age of 17 either during or shortly after the Battle of Wakefield, during the Wars of the Roses.

Supporting paragraphs: Richard Plantagenet (Richard of Eastwell) Richard III of England
Answer: the Battle of Bosworth Field