His family was descended from the Maguire chiefs of Fermanagh but were dispossessed of their lands and all they had left was a small farm in Killesher.
The major was born in Ballymagovern, County Cavan on 16 April 1746, the grandson of Colonel Bryan Magauran, the Chief of the Clan McGovern who fought in the Battle of the Boyne for King James II against William III of Orange.
At the time of Dr. Maguire's appointment as Bishop of Dromore, Edward M'Gauran was then serving as an ensign in General Loudon's Austrian Regiment of Foot.
He needed his pedigree proved by a respectable witness in Ireland and he states as follows; "My relations being numerous, and dispersed throughout the kingdom, I was several months employed in collecting their attestations , which I found was necessary to have corroborated by the testimony of Dr. Reilly, the Titular Bishop of Kilmore, who was then absent: I applied to Dr. M’Guire, the Catholic Bishop of Dromore, then at the house of Mr. Robert M’Guire of Tempo; He refused to grant me my request, although he knew my pretensions to be just.
Exasperated by his duplicity, which was injurious to my purpose and his tenets, I set off, and travelling all night, arrived the next morning at Kilmore, the seat of Dr. Craddock, the Protestant Bishop, who signed my certificate, which was followed by the dignified clergy, and the nobility of the neighbourhood, which I thought an ample indemnification for my recent disappointment".
James Cowan OFM, Guardian of St.Isidore's College, prepared an appeal in Italian to the Papacy on Hugh Maguire's behalf.).
Laurence Taaffe, Canon of Armagh, protested bitterly to Cardinal Antonelli of Propaganda in April 1784 at the conduct of Dr.Maguire.
The churches he caused to be built in Kilmore were Tullaghan (Kinlough) in 1770, Inishmagrath 1770, Laragh 1770, Kilmainhamwood 1775, Cavan 1774, Knocktemple (Castlerahan) 1780, Ballyconnell 1780, Bunnoe 1780, Tierworker 1788, Kildallan 1785, Killeshandra 1790, Ballinagh 1790, Killoughter 1790, Glenade 1790, Kilargue 1791, Corronea reconstructed 1795, Kildoagh 1797 & Derrylin 1797.
In 1778 he was the chief signatory of an address from 'The Catholics of County Fermanagh', signed by 24 persons to King George III offering support for his war against Revolutionary France.
The strain of reorganising the diocese told on Dr. Maguire's health and in 1792 he was given a Coadjutor in the person of Reverend Charles O'Reilly, who was appointed as such with the title of Bishop of Fussala, in partibus, on 17 May 1793.
Dr. Maguire died at Enniskillen, County Fermanagh on 23 December 1798 at the age of 77 and was succeeded as Bishop of Kilmore by Dr. Charles O'Reilly.
Being perfectly sound in mind, and tolerably well in body, to guard against a surprise, death being certain and the hour unknown, I make this my last will and testament, and dispose of all my worldly substance in the following manner.
I leave all my books, Latin, French & English, in charge of my nephew, Denis, as it may happen that some of my relatives may get a call to the Church, I desire the Lives of the Saints by Alban Butler to be always preserved in the family.
Should Mr. Hassard choose at any period to return the two hundred pounds, I order said money to be equally divided amongst the descendants male and female (I mean immediate descendants) of my brothers Bryan and Philip, excluding at the same time Bryan's two sons Hugh and Oliver, and Tery, Philip's son, from any dividend of said money.