On Pentecost 1440, or the day after, May 15 or 16, Gilles de Rais led an ambush of fifty or sixty men in a wood near Saint-Étienne-de-Mer-Morte, walked armed into the parish church in the middle of Mass, and threatened to kill the officiating cleric, Jean Le Ferron, with a guisarme unless he came out. He had sold the castle there to Le Ferron's brother Geoffroy, treasurer to John V, Duke of Brittany, and now wanted it back. He locked Le Ferron in the castle and had other ducal officers roughed up. In one act he had violated the immunity of the church and laid hands on the duke's servants, inside the diocese of Nantes, whose bishop, Jean de Malestroit, was chancellor of Brittany and in the words of the historian Joël Cornette the man actually directing the duchy's policy. Within four months he was under arrest for the murder of children.
He was born at the Château de Champtocé, in a room called the Black Tower, probably not before 1405. He was the eldest son of Guy de Laval, who took the name of Rais, and Marie de Craon, and heir to several of the great houses of western France. His father died in October 1415, and his maternal grandfather, Jean de Craon, raised him and his brother René, ignoring the father's will. The Craon family lost heavily at Agincourt that month. Two arranged betrothals fell through, and then Gilles abducted his cousin Catherine de Thouars and married her in 1422 without a dispensation or the banns; the church later separated them for incest and let them remarry. Their only child, Marie, was born in 1433 or 1434.
In April 1429 he allied himself with his cousin Georges de La Trémoille, the grand chamberlain of France, and joined the army assembling to relieve Orléans. He took part in the storming of the Saint-Loup bastille on May 6, 1429, rode in the same campaigns as Joan of Arc that year, and on September 8, during the failed assault on Paris, was one of the two captains she wanted beside her at the Porte Saint-Honoré. He was made a Marshal of France in 1429. In August 1432 he helped lift the siege of Lagny. Historians count him among Joan's comrades in arms without making him a close associate. His income has been estimated at about fifty thousand livres a year, nearly twenty thousand of it from his office as marshal. By 1435 his family was accusing him of squandering the inheritance, and in July that year Charles VII placed his lands under interdict.
He withdrew from military life in 1434 and 1435. According to the testimony of the priest Eustache Blanchet and the Tuscan cleric François Prelati, whom Blanchet recruited in Florence in 1438, Gilles sought alchemists to make gold, and at Tiffauges Prelati tried to summon a demon named Barron in his presence, with Gilles signing a pact for riches. When no demon appeared, Prelati said Barron wanted parts of a child, and Gilles supplied them in a glass vessel. In his own confession Gilles dated his first assaults on children to between spring 1432 and spring 1433.
After Saint-Étienne-de-Mer-Morte the church opened a secret inquiry into his reputation, and Bishop Malestroit made a pastoral visit through the parishes around the Hôtel de la Suze, Gilles's residence in Nantes, asking about missing children. Peasants from the villages near his castles said that their children had gone to his gates begging for food and had not come back. On July 29, 1440, the bishop published letters accusing him by public rumor of raping and murdering many children and of invoking demons. The secular court heard the same witnesses through its own investigator. On August 24 the duke, needing an ally after his part in the Praguerie revolt against the king, gave his brother, the Constable Arthur de Richemont, one of Gilles's lordships. On September 15, 1440, Jean Labbé, a captain in the duke's service, arrested Gilles at Machecoul. Prelati, Blanchet, the servants Henriet Griart and Étienne Corillaut, called Poitou, and two women accused of procuring children, Tiphaine Branchu and Perrine Martin, known as la Meffraye, were arrested with him. Two of his cousins, Gilles de Sillé and Roger de Briqueville, had apparently already fled.
He was tried in October before the church court on charges of murdering children, sodomy, invoking demons and heresy, and before the duke's court for murder. The weight of the witness testimony convinced the judges, and after he admitted the charges on October 21 the court dropped a plan to torture him into confessing. On October 23 the secular court heard the confessions of Poitou and Henriet and condemned them. Gilles was sentenced on October 25. The church court's sentence charged him with the murders of "one hundred and forty children, or more"; the secular sentence spoke only of several small children. He was allowed confession, and his request to be buried in the Carmelite church in Nantes was granted.
At nine in the morning on Wednesday, October 26, 1440, he and his two servants were taken to the place of execution on the Île de Biesse. He is said to have spoken to the crowd with contrite piety and urged Henriet and Poitou to die bravely and think only of their salvation. He had asked to die first. At eleven the brush was lit and he was hanged; his body was cut down before the flames reached it and claimed by four ladies of high rank for burial. The two servants' bodies were burned to ashes and scattered.
No contemporary portrait or description of him survives; every image is posthumous invention. Since the early nineteenth century he has been linked with Bluebeard, though the idea that he inspired Charles Perrault's tale of 1697 is speculation. His guilt has been questioned, most loudly in November 1992, when the writer Gilbert Prouteau staged an unofficial mock retrial in a hall of the Luxembourg Palace in Paris, where a panel of lawyers, politicians and writers found him not guilty. No medievalist was consulted, and historians including Michel Balard, Jean Kerhervé and Olivier Bouzy criticized its errors and inventions. Most professional historians reject claims of his innocence. They point to the detailed testimony of the parents of missing children, and to confessions from his servants that have no parallel in other inquisitorial records.