His followers forced the Dictum of Kenilworth after his death, which came a year after this disciple of Robert Grosseteste defeated his rival Richard of Cornwall at (*) Lewes.
This man's sons were excommunicated for viciously murdering his nephew, Henry of Almain, on a church altar. The de Clares abandoned this man shortly after he signed the Treaty of Pipton, cementing his alliance with Llywelyn the Last. His followers forced the Dictum of Kenilworth after his death, which came a year after this disciple of Robert Grosseteste defeated his rival Richard of Cornwall at (*) Lewes. The future Edward Longshanks impersonated this man's son, luring him into a fatal clash at Evesham in a conflict waged by this man to assert the Provisions of Oxford. Known for instituting the first directly elected parliament, for 10 points, name this man who ruled England for a year while waging the Second Barons' War against Henry III.
This man's sons were excommunicated for viciously murdering his nephew, Henry of Almain, on a church altar.
{Simon} de {Montfort}, 6th {Earl} of {Leicester} [accept either underlined portion]