In 1314 he was already able to wear knightly panoply of war, and in the following year he accompanied the royal army in an aimless expedition to Flanders, while his mother stayed at home and had prayers recited for the safety of her son. But that son, whom she loved so devotedly, and whom she was doing so much to please and amuse, did not live to manhood, for he died in the early part of September, 1317, before he had received the final dignity of knighthood. From all the Church dignitaries of Artois, from all the great relatives of Mahaut, came letters of condolence upon the death of the heir of Artois, which for two days was publicly proclaimed by servants of the countess through the streets of Paris, in which city generous alms were distributed to the poor; while pilgrims were despatched at once to Saint-James of Compostella, to Saint-Louis of Marseilles, and to other shrines, to intercede for the soul of the dead. A few weeks later Mahaut ordered a sculptor, Jean Pépin de Huy, to erect a tomb for the _très noble homme monseigneur Robert d'Artois, jadis fiuz (fils) de ladite comtesse_. This tomb, of white stone, bears a recumbent figure of the young count, clothed in armor, with long, flowing hair about the handsome, beardless face; it is now preserved in the Abbey of Saint-Denis, having been moved from the church of the Cordeliers, where it originally rested over the grave of Mahaut's son. Long before the death of Robert, the Countess Mahaut's daughters had played their brief and disastrous parts in the French court. In January, 1307, in accordance with the treaty agreed to by Count Otho in 1291, the eldest daughter, Jeanne, was married to Philippe de Poitiers, second son of King Philippe le Bel. The next year, Blanche, a great deal younger than Jeanne, but already renowned for her unusual beauty, married Charles le Bel, Count de la Marche, the youngest of the three sons of Philippe le Bel, Louis le Hutin, the eldest, having married Marguerite, sister of Hugues de Bourgogne. After their marriage to the princes of France, we hear little more of Jeanne and Blanche in the accounts of their mother, though both were guests at her mansion rather frequently, and presents of various sorts were exchanged between mother and daughters, until in 1314 came the great catastrophe.