Task: Question Understanding
Input (English): Passage: The conspirators fled to the western counties and raised the standard of rebellion. However, they obtained little support and were quickly apprehended by local authorities. While attempting to seize Cirencester, Lumley was beheaded in a short but violent skirmish by the townsfolk and Salisbury and Kent were captured. Held briefly in custody, they were abruptly beheaded without trial on 7 January 1400. Le Despencer was captured at Bristol by a mob and was also summarily beheaded on 13 January 1400. Huntingdon was captured at Pleshey and dealt with likewise on 16 January 1400. Blount escaped to Oxford, where he was hanged, drawn and quartered on 12 January 1400. Brocas was captured in Cirencester and beheaded at Tyburn. Those executed were subsequently attainted in March; the brother of Kent and the sons of Salisbury and Huntingdon were later restored to their fathers' titles. The attainders were formally reversed in 1461 by a Yorkist parliament. The rebellion also convinced Henry IV that a deposed, imprisoned and alive King Richard was a very dangerous liability for him. The deposed monarch would come to his death 'by means unknown' in Pontefract Castle by 17 February 1400.
Question: What year were the conspirators attainted?
Output (English): date