Question: When did Bobby Sands' hunger strike end?

full_context: Document 1: Bobby Sands: Robert Gerard Sands (Irish: "Roibeárd Gearóid Ó Seachnasaigh" ; 9 March 19545 May 1981), commonly known as Bobby Sands, was an Irish member of the Provisional Irish Republican Army who died on hunger strike while imprisoned at HM Prison Maze.
Document 2: Bobby Sands: 66 Days: Bobby Sands: 66 Days is a 2016 Irish documentary film about Bobby Sands and the 1981 Irish hunger strike.
Document 3: Maze Prison escape: The Maze Prison escape (known to Irish republicans as the Great Escape) took place on 25 September 1983 in County Antrim, Northern Ireland. HM Prison Maze (also known as Long Kesh) was a maximum security prison considered to be one of the most escape-proof prisons in Europe, and held prisoners convicted of taking part in armed paramilitary campaigns during the Troubles. In the biggest prison escape in UK history, 38 Provisional Irish Republican Army (IRA) prisoners escaped from H-Block 7 (H7) of the prison. One prison officer died of a heart attack as a result of the escape and twenty others were injured, including two who were shot with guns that had been smuggled into the prison. The escape was a propaganda coup for the IRA, and a British government minister faced calls to resign. The official inquiry into the escape placed most of the blame onto prison staff, who in turn blamed the escape on political interference in the running of the prison.
Document 4: Raymond McCreesh: Raymond McCreesh (Irish: "Réamonn Mac Raois" , 25 February 1957 – 21 May 1981) was a volunteer in the South Armagh Brigade of the Provisional Irish Republican Army (IRA). In 1976, he and two other IRA volunteers were captured while attempting to ambush a British Army observation post. McCreesh was one of the ten Irish republicans who died in the 1981 Irish hunger strike in the Maze Prison.
Document 5: Christy Moore: Christopher Andrew "Christy" Moore (born 7 May 1945) is an Irish folk singer, songwriter and guitarist. He is one of the founding members of Planxty and Moving Hearts. His first album, "Paddy on the Road" was recorded with Dominic Behan in 1969. In 2007, he was named as Ireland's greatest living musician in RTÉ's People of the Year Awards.
Document 6: 1981 Irish hunger strike: The 1981 Irish hunger strike was the culmination of a five-year protest during The Troubles by Irish republican prisoners in Northern Ireland. The protest began as the blanket protest in 1976, when the British government withdrew Special Category Status for convicted paramilitary prisoners. In 1978, after a number of attacks on prisoners leaving their cells to "slop out", the dispute escalated into the dirty protest, where prisoners refused to leave their cells to wash and covered the walls of their cells with excrement. In 1980, seven prisoners participated in the first hunger strike, which ended after 53 days.
Document 7: HM Prison Maze: Her Majesty's Prison Maze (previously Long Kesh Detention Centre and known colloquially as the Maze Prison, The Maze, the H Blocks or Long Kesh) was a prison in Northern Ireland that was used to house paramilitary prisoners during the Troubles from mid-1971 to mid-2000.
Document 8: Some Mother's Son: Some Mother's Son is a 1996 film written and directed by Irish filmmaker Terry George, co-written by Jim Sheridan, and based on the true story of the 1981 hunger strike in the Maze Prison, in Northern Ireland. Provisional Irish Republican Army (IRA) prisoner Bobby Sands (played by John Lynch) led a protest against the treatment of IRA prisoners, claiming that they should be treated as prisoners of war rather than criminals. The mothers of two of the strikers, played by Helen Mirren and Fionnula Flanagan, fight to save their sons' lives. When the prisoners go on hunger strike and become incapacitated, the mothers must decide whether to abide by their sons' wishes, or to go against them and have them forcibly fed.
Document 9: Roll of Honour (song): Roll of Honour is an Irish Republican song, written by Gerry O'Glacain, that commemorates the 10 IRA and INLA hunger strikers who died during the 1981 Irish hunger strike in Northern Ireland. The names each of the men are contained in the lyrics of the song in the order that they died: Bobby Sands, (Francis) Hughes, Ray McCreesh, (Patsy) O'Hara, Joe McDonnell, Martin Hurson, Kevin Lynch, Kieran Doherty, Thomas McElwee and Michael Devine. The song describes the 10 as "Ireland’s bravest men" who were "Hungering for justice" and "For their rights as Irish soldiers and to free their native land". The song ends with the call to "Fight on and make our homeland a nation once again".
Document 10: Anti H-Block: Anti H-Block was the political label used in 1981 by supporters of the Irish republican hunger strike who were standing for election in both Northern Ireland and the Republic of Ireland. "H-Block" was a metonym for the Maze Prison, within whose H-shaped blocks the hunger strike was taking place.
Document 11: Banna Strand (song): "Banna Strand" (also known as "The Lonely Banna Strand" - "The Ballad of Roger Casement" is a different song) is an Irish rebel song about the failed transport of arms into Ireland for use in the Easter Rising. Authorship of the song is unknown. The final verse was written by Derek Warfield of the Wolfe Tones in 1965 when Roger Casement's remains were finally returned to Ireland.
Document 12: The Spirit of Freedom: The Spirit of Freedom is an Irish folk music album by Christy Moore. The album is notable for featuring two songs penned by Irish hunger striker Bobby Sands. The songs "Back Home In Derry" and "McIlhatton" where written by Sands while in prison at Long Kesh.
Document 13: Bessbrook landmine attack: The Bessbrook landmine attack happened on the 19 May 1981 during a period of heightened tension in Northern Ireland over the 1981 Irish hunger strike and the death of Bobby Sands MP on the 5 May.
Document 14: Freedom and Rain: Freedom and Rain is a 1990 album by British folk rock band Oysterband and singer June Tabor. The album features a mixture of traditional material and contemporary covers including "Lullaby of London" by Shane MacGowan, "All Tomorrow's Parties" by Lou Reed, "Valentine's Day Is Over" by Billy Bragg and "Night Comes In" by Richard Thompson.
Document 15: 1980–81 British Home Championship: The 1980-81 British Home Championship was the only British Home Nations international football championship, other than the years of the First World War and Second World War, which was not completed and thus failed to produce a winner. As with the rugby union 1972 Five Nations Championship the cause of this cancellation was The Troubles in Northern Ireland. The championship was scheduled to be played in May 1981 after the termination of the domestic season. On 5 May, however, the Provisional Irish Republican Army hunger strike leader Bobby Sands died in the Maze Prison, invoking a storm of protest and violence by republicans in Northern Ireland. Thus the English and Welsh FAs, whose teams were scheduled to travel to Windsor Park later in the month, declined to play, rendering the tournament incomplete and void.
ground_truth: after 53 days