Question: Who is Robert Iv Of Artois, Count Of Eu's paternal grandfather?

Knowledge 1: Robert IV of Artois, Count of Eu
Robert IV of Artois (1356 – July 20, 1387), son of John of Artois, Count of Eu and Isabeau of Melun, was Count of Eu from April to July 1387.About 1376, he married Joanna of Durazzo, daughter of Charles, Duke of Durazzo.Robert IV inherited the County of Eu on April 6, 1387 along with Saint-Valery and Ault, however, in Naples at the time, he never learned of his father's death.He and his wife were poisoned whilst staying at Castel dell'Ovo on July 20, 1387 on the orders of Joanna's own sister Margaret, Queen Regent of Naples.Robert and Joanna were buried in the church of San Lorenzo Maggiore in Naples.The marriage of Robert and Joanna had remained childless.Robert was succeeded in Eu by his younger brother Philip of Artois, Count of Eu. [SEP] Knowledge 2: John of Artois, Count of Eu
John of Artois (29 August 1321 – 1387), called "sans Terre" (Lackland), was the son of Robert III of Artois and Joan of Valois.The confiscation of his father's goods for attempted fraud in 1331 had left him without an inheritance.In 1352, he was created Count of Eu, a title earlier forfeited at the execution of the previous holder, Raoul II of Brienne.He was badly wounded at the Battle of Poitiers on 19 September 1356, and was captured there by the English.Enormously rich his ransom was sold to the Black Prince by his captor Élie de Pommiers for 30,000 old écus.He married Isabeau of Melun (1328–1389), daughter of John I of Melun, Count of Tancarville, on 11 July 1352 and had the following issue:
Knowledge 1: Robert IV of Artois, Count of Eu
Robert IV of Artois (1356 – July 20, 1387), son of John of Artois, Count of Eu and Isabeau of Melun, was Count of Eu from April to July 1387.About 1376, he married Joanna of Durazzo, daughter of Charles, Duke of Durazzo.Robert IV inherited the County of Eu on April 6, 1387 along with Saint-Valery and Ault, however, in Naples at the time, he never learned of his father's death.He and his wife were poisoned whilst staying at Castel dell'Ovo on July 20, 1387 on the orders of Joanna's own sister Margaret, Queen Regent of Naples.Robert and Joanna were buried in the church of San Lorenzo Maggiore in Naples.The marriage of Robert and Joanna had remained childless.Robert was succeeded in Eu by his younger brother Philip of Artois, Count of Eu. [SEP] Knowledge 2: Philip of Artois, Count of Eu
Philip of Artois( 1358 – 16 June 1397, Micalizo), son of John of Artois, Count of Eu, and Isabeau of Melun, was Count of Eu from 1387 until his death, succeeding his brother Robert.Philip was a gallant and energetic soldier.In 1383, he captured the town of Bourbourg from the English.He went on a pilgrimage to the Holy Land, and was imprisoned there by Barquq, the Sultan of Egypt, being released through the mediation of Jean Boucicaut and the Venetians.In 1390, he joined the unsuccessful expedition of Louis II, Duke of Bourbon, against Mahdia.In 1392, he was created Constable of France.On 27 January 1393 he married Marie( 1367 – 1434), daughter of John, Duke of Berry.They had four children:As a prominent Crusader, he was one of the French contingent sent to take part in the Battle of Nicopolis.He was captured in the battle, and subsequently died in captivity.
Knowledge 1: John of Artois, Count of Eu
John of Artois (29 August 1321 – 1387), called "sans Terre" (Lackland), was the son of Robert III of Artois and Joan of Valois.The confiscation of his father's goods for attempted fraud in 1331 had left him without an inheritance.In 1352, he was created Count of Eu, a title earlier forfeited at the execution of the previous holder, Raoul II of Brienne.He was badly wounded at the Battle of Poitiers on 19 September 1356, and was captured there by the English.Enormously rich his ransom was sold to the Black Prince by his captor Élie de Pommiers for 30,000 old écus.He married Isabeau of Melun (1328–1389), daughter of John I of Melun, Count of Tancarville, on 11 July 1352 and had the following issue: [SEP] Knowledge 2: Joan of Valois, Countess of Beaumont
Joan of Valois (1304–1363) was the daughter of Charles of Valois and his second wife Catherine I of Courtenay, titular empress of Constantinople.Half sister to Philip VI of Valois, in around 1320 she married Robert III of Artois, Count of Beaumont-le-Roger and seigneur of Conches.They had five known children:
Robert III of Artois had attempted to recover the title of count of Artois, which had been taken from him by his aunt Mahaut of Artois, but was condemned and exiled in 1331 for making and presenting forged documents in the process of filing against her.Joan of Valois and their children were therefore imprisoned by order of her half-brother Philip VI.

Answer: Robert III of Artois