Thomas Preston , 1st Viscount Tara Thomas Preston , 1st Viscount Tara ( 1585 – 1655 ) was an Irish soldier of the 17th century . Linage . Preston was a descendant of Robert Preston , 1st Baron Gormanston , who in 1363 purchased the lands of Gormanston , County Meath , and who was Lord Chancellor of Ireland in 1388 . Sir Robert ' s great - grandson , Robert Preston , was created Viscount Gormanston in 1478 ; and the latter ' s great - grandson was Christopher , 4th Viscount Gormanstown ( d . 1599 ) , whose second son was Thomas Preston . Biography . Thomas ' s elder brother succeeded the title of Viscount Gormanstown , so Thomas Preston pursued a career in the military . Since Roman Catholics were not allowed to hold state positions in Ireland , he entered the Spanish service and fought in the Thirty Years ' War . Preston was in the same Irish regiment in the Spanish service as Owen Roe O ' Neill , and distinguished himself in the defence of Leuven against the French and Dutch in 1635 . Between him and Owen Roe O ' Neill there was from the first intense jealousy . There was also some tension between Preston and James Tuchet . In 1644 Tuchet , the Earl of Castlehaven was chosen to lead a major Confederate expedition into Ulster . Unlike Preston , Castlehaven was a military amateur but was he favoured over Preston as he was of a prominent English family . Preston returned to Ireland after the Irish Rebellion of 1641 to support his fellow Irish Catholics . He was appointed general of Leinster , by the Irish Confederates , which was the largest and best equipped of the Irish Catholic forces . His performance as a commander in Ireland in the intermittent wars if 1642 to 1652 was mixed . He won widespread praise for his successful siege of Duncannon in 1645 , but lost a string of field battles including New Ross ( 1643 ) and Dungans Hill ( 1647 ) . This last battle was disastrous for the Confederates , as their Leinster army was all but wiped out at it . In general he was skilled in the art of siegecraft , but never had a very good understanding of mobile warfare . Preston played a major part in the Confederates ' internal strife , siding at first with radicals who opposed the first Ormonde peace , but later siding with the moderates who signed a conclusive treaty with Ormonde and the Royalists in 1648 . His Royalism was motivated by his Old English roots and his extreme personal dislike of Owen Roe O ' Neill , who led the opposing faction . He fought with the defeated Royalists during the Cromwellian conquest of Ireland - defending the city of Waterford until hunger and disease forced him to capitulate . He marched his remaining troops to Galway , the last Irish held city on the island . In late 1652 , after another lengthy siege , Galway too was reduced by plague and lack of supplies . Preston surrendered the city on condition that he and his troops be allowed to leave the country and find employment in the French army . He left the country for exile in France - where the Royalist court was in exile - in 1652 . In 1650 Charles II while in exile created him Viscount Tara ; and after his departure from Ireland in 1652 he offered his services to Charles in Paris , where he died in October 1655 . Family . Preston ' s wife was a Flemish lady of rank , by whom he had several children , one of his daughters being the second wife of Sir Phelim O ' Neill . His son Anthony succeeded him as 2nd Viscount Tara , a title that became extinct on the death of Thomas , 3rd Viscount , in 1674 .