Question: Whose son's death brought titles to Edward III's most trusted captain?
Context: The House of York was a cadet branch of the English royal House of Plantagenet.  Three of its members became Kings of England in the late 15th century.  The House of York was descended in the male line from Edmund of Langley, 1st Duke of York, the fourth surviving son of Edward III, but also represented Edward's senior line, being cognatic descendants of Lionel, Duke of Clarence, Edward III's second surviving son.  It is based on these descents that they claimed the English crown.  Compared with the House of Lancaster, it had a senior claim to the throne of England according to cognatic primogeniture but junior claim according to the agnatic primogeniture.  The reign of this dynasty ended with the death of Richard III of England in 1485.  It became extinct in the male line with the death of Edward Plantagenet, 17th Earl of Warwick in 1499. The House of Lancaster was the name of two cadet branches of the royal House of Plantagenet.  The first house was created when Henry III of England created the Earldom of Lancasterfrom which the house was namedfor his second son Edmund Crouchback in 1267.  Edmund had already been created Earl of Leicester in 1265 and was granted the lands and privileges of Simon de Montfort, 6th Earl of Leicester, after de Montfort's death and attainder at the end of the Second Barons' War.  When Edmund's son Thomas, 2nd Earl of Lancaster, inherited his father-in-law's estates and title of Earl of Lincoln he became at a stroke the most powerful nobleman in England, with lands throughout the kingdom and the ability to raise vast private armies to wield power at national and local levels.  This brought himand Henry, his younger brotherinto conflict with their cousin Edward II of England, leading to Thomas's execution.  Henry inherited Thomas's titles and he and his son, who was also called Henry, gave loyal service to Edward's sonEdward III of England. The Barony of Courtenay, called Baron Courtenay, was created in 1299.  The Earldom was confirmed by King Edward III and conferred on Hugh de Courtenay, Earl of Devon's summons to be a Lord of Parliament during his father's lifetime on 23 April 1337.  This was Edward III's first Parliament as an adult king in charge of his own rule, and all writs were codified in Latin; Hugh was styled "Hugoni de Courteney juniori".  The writ of title was originally by Edward I in 1299.  His father died at Christmas 1340, whence Hugh became Earl of Devon.  Cokayne discussed the summons and esoteric point as to whether the writ had its origination in 1337 or earlier.  In essence the title was a courtesy for the earldom, bestowed upon the eldest son and heir apparent. King Duncan is a fictional character in Shakespeare's "Macbeth."  He is the father of two youthful sons (Malcolm and Donalbain), and the victim of a well-plotted regicide in a power grab by his trusted captain Macbeth.  The origin of the character lies in a narrative of the historical Donnchad mac Crinain, King of Scots, in Raphael Holinshed's 1587 "The Chronicles of England, Scotland, and Ireland," a history of Britain familiar to Shakespeare and his contemporaries.  Unlike Holinshed's incompetent King Duncan (who is credited in the narrative with a "feeble and slothful administration"), Shakespeare's King Duncan is crafted as a sensitive, insightful, and generous father-figure whose murder grieves Scotland and is accounted the cause of turmoil in the natural world. Henry of Grosmont, 1st Duke of Lancaster, 4th Earl of Leicester and Lancaster, KG (c. 1310 – 23 March 1361), also Earl of Derby, was a member of the English nobility in the 14th century, and a prominent English diplomat, politician, and soldier.  The son and heir of Henry, 3rd Earl of Lancaster, and Maud Chaworth, he became one of Edward III's most trusted captains in the early phases of the Hundred Years' War and distinguished himself with victory in the Battle of Auberoche.  He was a founding member and the second Knight of the Order of the Garter in 1348, and in 1351 was created duke.  An intelligent and reflective man, Grosmont taught himself to write and was the author of the book "Livre de seyntz medicines", a highly personal devotional treatise.  He is remembered as one of the founders and early patrons of Corpus Christi College, Cambridge, which was established by two of the guilds of the town in 1352. Edmund of Langley, 1st Duke of York, KG (5 June 1341 – 1 August 1402) was the fourth surviving son of King Edward III of England and Philippa of Hainault.  Like many medieval English princes, Edmund gained his nickname from his birthplace: Kings Langley Palace in Hertfordshire.  He was the founder of the House of York, but it was through the marriage of his younger son, Richard of Conisburgh, 3rd Earl of Cambridge, to Anne de Mortimer, great-granddaughter of Edmund's elder brother Lionel of Antwerp, 1st Duke of Clarence, that the House of York made its claim to the English throne in the Wars of the Roses.  The other party in the Wars of the Roses, the incumbent House of Lancaster, was formed from descendants of Edmund's elder brother John of Gaunt, 1st Duke of Lancaster, Edward III's third son. The El Cazador (meaning "The Hunter" in English) was a Spanish brig that sank in the Gulf of Mexico in 1784.  On 20 October 1783 Charles III of Spain sent her on a mission to bring much-needed hard currency to the Spanish colony of Louisiana.  The ship sailed to Veracruz, Mexico, where she was loaded with approximately 450,000 Spanish reales.  King Carlos III enlisted his most trusted captain, Gabriel de Campos y Pineda, to command the ship.  On 11 January 1784, she sailed for New Orleans, and was never heard from again.  Spain’s attempts to locate the ship were unsuccessful and in June 1784, "El Cazador" was officially listed as missing at sea. Richard II (6 January 1367 – c. 14 February 1400), also known as Richard of Bordeaux, was King of England from 1377 until he was deposed on 30 September 1399.  Richard, a son of Edward, the Black Prince, was born in Bordeaux during the reign of his grandfather, Edward III.  His father was Prince of Aquitaine.  Richard was the younger brother of Edward of Angoulême, upon whose death Richard, at three years of age, became second in line to the throne after his father.  Upon the death of Richard's father prior to the death of Edward III, Richard, by primogeniture, became the heir apparent to the throne.  With Edward III's death the following year, Richard succeeded to the throne at the age of ten. Edward III of England is the central character in the play "Edward III", sometimes attributed to William Shakespeare.  He also appears as a boy in "Edward II" by Christopher Marlowe.  Edward is also the protagonist of William Blake's early drama "Edward the Third", part of his "Poetical Sketches", published in 1783.  George Bernard Shaw portrayed Edward for dramatic purposes as, in Shaw's preface to "The Six of Calais", "behaving himself like an unrestrained human being in a very trying situation". Edward III (13 November 1312 – 21 June 1377) was King of England from 25 January 1327 until his death; he is noted for his military success and for restoring royal authority after the disastrous and unorthodox reign of his father, Edward II.  Edward III transformed the Kingdom of England into one of the most formidable military powers in Europe.  His long reign of 50 years was the second longest in medieval England and saw vital developments in legislation and government—in particular the evolution of the English parliament—as well as the ravages of the Black Death.
Answer: Thomas, 2nd Earl of Lancaster