In the early morning of Friday, 13 March 1271 (12 March, Ann. Winton. p. 110), the kings of France and Naples were at mass in the church of the Franciscans. Henry was also attending service at one of the parish churches of the town situated opposite his lodgings (Fœdera, i. 501, ‘Processus Papæ contra G. de Monteforte’). This was probably the church of San Silvestro (Ann. Winton.; Oxenedes, p. 239; Flores Historiarum, p. 350, ed. 1570, and Cont. John de Tayster, Landino, Velutello). But some authorities send Henry to church in the cathedral of S. Lorenzo (Rishanger, Trivet, Guillaume de Nangis, Primat). Wykes makes it the church of the confraternity of S. Biagio (see for these churches Bussi, Istoria di Viterbo). The most authoritative sources speak very vaguely of ‘a certain church or chapel’ (e.g. letter of Philip III to the king of the Romans in Lib. de Antiquis Legibus, p. 133; Wykes, p. 237; Ann. Osney, p. 243; Hemingburgh, i. 331; G. Villani; Oberti Stanconi, &c., Ann. Januenses).
Henry was kneeling at prayer before the high altar when a band of armed men burst violently into the church. At their head was Guy de Montfort, who as he entered cried out in a loud voice, ‘Traitor, Henry of Almaine, thou shalt not escape’ (Fœdera, i. 501). He was followed by his brother Simon and his father-in-law Rosso. Taken utterly by surprise Henry was seized with a sudden panic, and rushed for sanctuary to the altar, clinging to it with his hands, and crying for mercy. He was fiercely attacked, and soon despatched with a multitude of wounds, the fingers of the hand that was clutching the altar being nearly cut off. Two clerks were also wounded in the confusion. ‘I have had my revenge,’ cried Guy, as he hurried from the church. ‘How so,’ replied one of his knights, ‘your father was dragged about’ (G. Villani in Muratori, xiii. 261, gives the very words in French in the midst of his Italian narrative). Guy then returned to the church, and dragged the body of his cousin by the hair right through the church to the piazza opposite, where it met with barbarous ill-treatment. The murderers then took horse, and found a refuge in Rosso's castle in the Maremma (‘in Montemfisconum,’ Ann. Placentini Gibellini; Mon. Germ. Scriptt. xviii. 550).
This cold-blooded murder excited universal horror, the more so as Henry was not even present at the death of Earl Simon, and had laboured for the reconciliation and return of his sons (Ann. Norm. in Mon. Germ. Scriptt. xxvi. 517). It was to little purpose that Philip of France wrote in terms of deep sympathy to King Richard, and Charles of Anjou sought to exculpate himself with Edward from the misdeeds of his vicar (Lib. de Ant. Leg. pp. 133–4; Fœdera, i. 488). Men generally blamed them for their weakness or their sluggishness. It was not until Edward, now king of England, appeared in Italy that strong measures were taken by Gregory X against the murderers (Fœdera, i. 501). But Simon was already dead, though Guy atoned for his crime by a long imprisonment and a miserable end. Dante put him in the seventh circle of hell, surrounded by a river of boiling blood (Inferno, xii. 118–20; cf. Commentary of Benvenuto of Imola in Muratori, Antiq. Ital. i. 1050 B). The men of Viterbo caused the story of the slaughter to be painted on the wall, and a copy of Latin verses inspired by the picture is preserved (Rishanger, p. 67, Rolls Ser.)
Henry of Almaine was a good soldier and a man of ability, though somewhat fickle and inconstant. His character was so attractive that both Simon de Montfort and Edward I had conceived the highest hopes of him. The more perishable parts of his body were buried at Viterbo ‘between two popes’ (Ann. Hailes in Mon. Germ. Scriptt. xvi. 483). His bones and heart were conveyed to England, arriving in London on 15 May. The heart, encased in a costly vase, was deposited in Westminster Abbey, near the shrine of the Confessor, where it became an object of popular veneration. Later Italian writers, misunderstanding Dante's reference (‘Lo cuor che 'n sul Tamigi ancor si cola’), have ludicrously inferred that it was put on the top of a column over London Bridge. Henry's bones were, by King Richard's direction, buried on 21 May at Hailes, his birthplace, next those of his stepmother, Sanchia, in the noble Cistercian abbey which his father had now erected there. The obsequies were carried out by the London Franciscans (Lib. de Ant. Leg. p. 134).
