Question: What is the date of death of John Browne, 1St Marquess Of Sligo's father?

Knowledge 1: John Browne, 1st Marquess of Sligo
John Denis Browne, 1st Marquess of Sligo, KP, PC(Ire) (11 June 1756 – 2 January 1809) was an Irish peer and politician, and was the son of Peter Browne, 2nd Earl of Altamont, and his wife Elizabeth, née Kelly, daughter of Denis Kelly, Chief Justice of Jamaica.Browne was styled Viscount Westport from 1771 to 1780 and known as John Browne, 3rd Earl of Altamont from 1780 to 1800.Browne represented Jamestown in the Irish House of Commons from 1776-1780, when he succeeded as Earl of Altamont.He served as High Sheriff of Mayo for 1779.He became Marquess of Sligo on 29 December 1800 and was appointed a Knight of the Order of St Patrick on 5 August 1800. [SEP] Knowledge 2: Peter Browne, 2nd Earl of Altamont
Peter Browne, 2nd Earl of Altamont (c. 1731 - 28 December 1780) was an Irish landowner and MP.He was the son of John Browne, 1st Earl of Altamont, and Anne Gore.He married Elizabeth Kelly, the only child of Denis Kelly, on 16 April 1752.Den(n)is Kelly was Chief Justice of Jamaica and the Brownes inherited the Jamaican sugar plantations as well as Lisduff estate and Spring Garden estate, both in the civil parish of Tynagh, Barony of Leitrim (County Galway).The townland of Lisduff exceeds 264 acres while the townland of Spring Garden exceeds 275 acres.The Lisduff estate was acquired from Denis Kelly's brother, Edmond Kelly.The estate was enlarged by land purchases in the townland of Drumatober (also in the Barony of Leitrim, Abbeygormacan civil parish) and Garrancarf in 1749, and of the lands of Cormickoge from John Burke in 1750.He adopted the additional surname of Kelly.He was elected Member of Parliament for Mayo in the Parliament of Ireland for 1761 to 1768.
Knowledge 1: John Browne, 1st Marquess of Sligo
John Denis Browne, 1st Marquess of Sligo, KP, PC(Ire) (11 June 1756 – 2 January 1809) was an Irish peer and politician, and was the son of Peter Browne, 2nd Earl of Altamont, and his wife Elizabeth, née Kelly, daughter of Denis Kelly, Chief Justice of Jamaica.Browne was styled Viscount Westport from 1771 to 1780 and known as John Browne, 3rd Earl of Altamont from 1780 to 1800.Browne represented Jamestown in the Irish House of Commons from 1776-1780, when he succeeded as Earl of Altamont.He served as High Sheriff of Mayo for 1779.He became Marquess of Sligo on 29 December 1800 and was appointed a Knight of the Order of St Patrick on 5 August 1800. [SEP] Knowledge 2: John Browne, 1st Earl of Altamont
John Browne, 1st Earl of Altamont( c.1709 – 4 July 1776), known as The Lord Mount Eagle between 1760 and 1768 and as The Viscount Westport between 1768 and 1771, was an Irish peer and politician.
Knowledge 1: John Browne, 1st Marquess of Sligo
John Denis Browne, 1st Marquess of Sligo, KP, PC(Ire) (11 June 1756 – 2 January 1809) was an Irish peer and politician, and was the son of Peter Browne, 2nd Earl of Altamont, and his wife Elizabeth, née Kelly, daughter of Denis Kelly, Chief Justice of Jamaica.Browne was styled Viscount Westport from 1771 to 1780 and known as John Browne, 3rd Earl of Altamont from 1780 to 1800.Browne represented Jamestown in the Irish House of Commons from 1776-1780, when he succeeded as Earl of Altamont.He served as High Sheriff of Mayo for 1779.He became Marquess of Sligo on 29 December 1800 and was appointed a Knight of the Order of St Patrick on 5 August 1800. [SEP] Knowledge 2: Randal William MacDonnell, 1st Marquess of Antrim
Randal William MacDonnell, 1st Marquess of Antrim was an Irish peer.

Answer: 28 December 1780