John Oldcastle was born in 1370 and in 1397 inherited his family estates, which included a manor in Almeley as well as lands in Kinnersley and Letton, Herefordshire, and property in and around Hereford.

[3][4] Increasingly radicalised in the years that followed, Oldcastle wrote letters to Hussite leaders Wok of Waldstein and Wladislas of Zwierzeticz, congratulating them on their opposition to the mainstream clergy.

The rise of Lollardy alarmed archbishop Thomas Arundel, who unsuccessfully accused Oldcastle of promoting heretical teachings within his estates on several occasions, despite to Henry's reluctance to allow the Church to prosecute a close personal friend.

Oldcastle seized the opportunity, escaping on 19 October with aid of a group of London Lollards led by William Parchmyner, and later going into hiding at latter's house in Smithfield.

Priest William Ederyk rallied Lollards in south Derbyshire, the Cok brothers formed a contingent in northern Essex, and pamphlets inciting resistance began circulating in Leicestershire.

Oldcastle realised that his plans were public but decided to pursue his goals of destroying Catholic churches and the houses of the friars, and overthrowing the king, as his supporters had already arrived at the St. Giles' Fields.

On the night of 9/10 January 1414, Henry gathered his troops at St. John's Priory, Clerkenwell, while sending patrols that would prevent insurgent reinforcements from reaching their main camp.

Charged with treason and heresy, all but one militant were burned at the stake or hanged, and commissions were sent to regions with known Lollard populations, detaining local heretics and rebels regardless of their participation in the revolt.

[2] Arrests continued as insurgent commanders Walter Blake and Sir Roger Acton were caught and executed, but Oldcastle managed to evade detainment with support of his old friend John ap Harry, who collected rents from his forfeited estates.