# Niall Garve O'Donnell

Niall Garve O'Donnell (Irish: Niall Garbh Ó Domhnaill; c. 1569 – 1626) was an Irish nobleman and soldier who claimed the lordship of Tyrconnell, alternately a rebel against and ally of English rule in Ireland. He is best known for siding with the English against his kinsman Hugh Roe O'Donnell during the Nine Years' War.
Although Niall's paternal grandfather was O'Donnell clan chief and Lord of Tyrconnell, his own father was passed over in favour of his half-uncle Hugh McManus O'Donnell. After a violent succession conflict, Hugh McManus's son Hugh Roe—Niall's younger cousin by two years—succeeded to the lordship in 1592. A long lasting bitterness ensued between the two cousins.
Niall initially fought for Hugh Roe and the Irish confederacy, but in 1600 he entered secret negotiations with leading royal soldier Henry Docwra. The English government hoped to harness Niall's feud against Hugh Roe and promised him the lordship of Tyrconnell for his military assistance. Niall defected in October bringing many followers with him.
Niall's skills in guerrilla warfare emboldened the English troops and allowed Docwra to significantly weaken Irish forces in Ulster. However, Niall's request that the English government not interfere with his promised lordship was incompatible with the Crown's plan for Ireland. After the war ended, Niall was not granted the lands or titles he was promised. In early 1608 Niall instigated fellow spurned loyalist Cahir O'Doherty to launch a rebellion in Derry, but he was quickly implicated and put on trial. Faced with a sympathetic jury that would almost certainly acquit, the government sent Niall to the Tower of London in 1609, where he remained until his death seventeen years later.
The O'Donel baronets of Newport House, County Mayo, were descended from Niall's grandson Rory.

## Family background

Family tree :
| | | | | Judith (Siobhán) O'Neill | Judith (Siobhán) O'Neill | Judith (Siobhán) O'Neill | Judith (Siobhán) O'Neill | | | | | Manus O'Donnell 1490–1564 | Manus O'Donnell 1490–1564 |
| | | | | | | | | | | | | | | | | | | | | | | | | | | Calvagh O'Donnell c. 1515–1566 | Calvagh O'Donnell c. 1515–1566 | Calvagh O'Donnell c. 1515–1566 | Calvagh O'Donnell c. 1515–1566 | Calvagh O'Donnell c. 1515–1566 | Calvagh O'Donnell c. 1515–1566 | Shane O'Neill c. 1530–1567 | Shane O'Neill c. 1530–1567 | Shane O'Neill c. 1530–1567 | Shane O'Neill c. 1530–1567 | Shane O'Neill c. 1530–1567 | Shane O'Neill c. 1530–1567 |
| | | | | | | | | | | | | | | Fiona "Iníon Dubh" MacDonald | Fiona "Iníon Dubh" MacDonald | Fiona "Iníon Dubh" MacDonald | Fiona "Iníon Dubh" MacDonald | Fiona "Iníon Dubh" MacDonald | Fiona "Iníon Dubh" MacDonald | Hugh McManus O'Donnell c. 1520–1600 | Hugh McManus O'Donnell c. 1520–1600 | Hugh McManus O'Donnell c. 1520–1600 | Hugh McManus O'Donnell c. 1520–1600 | Hugh McManus O'Donnell c. 1520–1600 | Hugh McManus O'Donnell c. 1520–1600 | Conn O'Donnell d. 1583 | Conn O'Donnell d. 1583 | Conn O'Donnell d. 1583 | Conn O'Donnell d. 1583 | Conn O'Donnell d. 1583 | Conn O'Donnell d. 1583 | Rose O'Neill | Rose O'Neill | Rose O'Neill | Rose O'Neill | Rose O'Neill | Rose O'Neill |
| Hugh Roe O'Donnell 1572–1602 | Hugh Roe O'Donnell 1572–1602 | Hugh Roe O'Donnell 1572–1602 | Hugh Roe O'Donnell 1572–1602 | Hugh Roe O'Donnell 1572–1602 | Hugh Roe O'Donnell 1572–1602 | Nuala O'Donnell c. 1575–c. 1630 | Nuala O'Donnell c. 1575–c. 1630 | Nuala O'Donnell c. 1575–c. 1630 | Nuala O'Donnell c. 1575–c. 1630 | Nuala O'Donnell c. 1575–c. 1630 | Nuala O'Donnell c. 1575–c. 1630 | Niall Garve O'Donnell c. 1569–1626 | Niall Garve O'Donnell c. 1569–1626 | Niall Garve O'Donnell c. 1569–1626 | Niall Garve O'Donnell c. 1569–1626 | Niall Garve O'Donnell c. 1569–1626 | Niall Garve O'Donnell c. 1569–1626 |
| XXX | XXX | XXX | XXX | XXX | XXX | Subject of the article | Subject of the article | Subject of the article | Subject of the article | Subject of the article | Subject of the article | XXX | XXX | XXX | XXX | XXX | XXX | King of Tyrconnell | King of Tyrconnell | King of Tyrconnell | King of Tyrconnell | King of Tyrconnell | King of Tyrconnell | XXX | XXX | XXX | XXX | XXX | XXX | O'Neill Chieftainship | O'Neill Chieftainship | O'Neill Chieftainship | O'Neill Chieftainship | O'Neill Chieftainship | O'Neill Chieftainship |
Niall Garve O'Donnell was born c. 1569 into the O'Donnell clan, the ruling Gaelic Irish noble family of Tyrconnell. He was the fourth or eldest son of Conn O'Donnell, the head of the O'Donnells' Clann-Dalaigh branch, and Rose O'Neill, daughter of the late O'Neill clan chief Shane O'Neill. Niall's sobriquet "Garve" meant "rough". According to historian Paul Walsh, "this epithet was traditional with the O'Donnells named Niall, and has no special significance in his case". Niall's ancestor, who ruled Tyrconnell from 1422 to 1439, was also named Niall Garve.
Niall had eight brothers, including Hugh Boye, Conn Oge, Donal Calvagh Oge, Cathbharr and Manus. He also had sisters named Róise, Elizabeth, Siobhan and Máire. As a child, Niall was fostered to the MacLeans of Scotland's Western Isles.
Niall's paternal grandfather was Calvagh O'Donnell, who was Lord of Tyrconnell and Chief of the Name O'Donnell. However, at the time of Calvagh's death in 1566, Calvagh's son Conn was a prisoner in the hands of Shane O’Neill. Thus the lordship passed instead to Calvagh's half-brother Hugh McManus O'Donnell. Conn and his descendants, particularly Niall, looked to the Dublin-based English government as a means of restoring their branch of the family to power. This branch established themselves in Lifford, between the River Finn and Lough Swilly. They were constantly at odds with the ruling O'Donnells.

## Succession dispute

In 1587, Hugh McManus's son and tanist Hugh Roe (also Niall's younger first cousin once-removed) was kidnapped on the orders of the Lord Deputy and imprisoned in Dublin Castle. Hugh McManus had become senile in his old age, and a violent succession dispute broke out amongst the greater O'Donnell family over who would succeed him. Three of Niall's brothers died during the conflict; in fact, six of his brothers would die in violent circumstances. Calvagh Oge died in 1588, and Manus died in 1589.
Hugh McManus's Scottish wife Iníon Dubh effectively took over leadership of Tyrconnell and devoted herself to defending Hugh Roe's claim to the chieftaincy. She used her Scottish redshanks to destroy rival claimants, including Calvagh's son Hugh MacEdegany in May 1588, and Hugh Roe's older half-brother Donal on 14 September 1590. Another elder cousin Hugh Dubh was also a competing claimant. After Hugh MacEdegany's death, Niall took over as the head of the MacCalvagh faction. Niall had a significant following within Tyrconnell, but it appears that he was not powerful enough to seriously provoke an assault from Iníon Dubh.
English forces took advantage of the clan's internal conflict and began pillaging and raiding across Tyrconnell. At one point Hugh McManus was kidnapped by Captain John Connill, but he was rescued by Niall.
Niall's closest ally was his neighbour Turlough Luineach O'Neill, who had succeeded Niall's maternal grandfather Shane as O'Neill clan chief. At the time Turlough was defending his lands from rival clansman Hugh O'Neill, Earl of Tyrone, who had formed an alliance with the ruling O'Donnell branch. On 1 May 1589, Niall fought alongside Turlough and defeated Tyrone in battle.
In 1591, Inion Dubh temporarily bought off Niall with a political marriage to her daughter—his first cousin once-removed—Nuala. This marriage was the family's attempt to temper Niall's hostility.

## Succession of Hugh Roe

Hugh Roe eventually escaped prison and returned to Tyrconnell in early 1592; Tyrone had bribed officials in Dublin to secure his release. Hugh McManus abdicated in favour of Hugh Roe in April 1592. Niall was incensed at his cousin's elevation to the chieftainship. Hugh Roe was inaugurated as clan chief on 3 May 1592, but Niall was conspicuously absent from the inauguration ceremony. Instead, he was in Dublin attempting to secure support from the government. His pleas were dismissed.
Soon after Hugh Roe's succession, Hugh Roe and Tyrone attacked Turlough. By May 1593 Turlough was eventually forced into a surrender. As Turlough was a major ally to Niall, this greatly weakened Niall's power in Ulster. In July 1592, Hugh Roe submitted to Lord Deputy FitzWilliam at Dundalk. They came to an agreement where FitzWilliam would conditionally overlook Hugh Roe's anti-royalist activities—one condition being that Niall be treated fairly.
To destroy his rivals, Hugh Roe surprised Hugh Dubh's garrison in Belleek castle, beheading the ward of Belleek and bringing Hugh Dubh to submission. Shortly afterwards, Niall submitted to Hugh Roe through intimidation. Though Niall attended Hugh Roe's first hosting, he did so ‘"not through love, but wholly through fear."
According to historian Terry Clavin, Hugh Roe was anxious to mend the divisions within the O'Donnell clan in order to make the Irish confederacy stronger. Clavin characterises Hugh Roe as trying to reconcile with Niall rather than suppress him.

## Irish confederacy

Niall fought for the Irish confederacy at the beginning of the Nine Years' War. On Hugh Roe's orders, he commanded 60 horsemen, 60 swordsmen and 100 gallowglass to the Battle of Belleek in October 1593. It was one of the first major battles of the war but was secretly planned to result in an Irish failure. This would divert English attention away from Ireland and make the Irish confederacy seem weaker than it actually was. As part of the plan, Hugh Roe was ordered by Tyrone not to send reinforcements. Historian James O'Neill has theorised that Hugh Roe intentionally dispatched Niall to Belleek with the hope that he would die in the slaughter, thus easily eliminating a potential enemy.
Niall's continuing belligerence led him to be detained in February 1594. He was only released when Hugh Roe received one of Niall's brothers as a pledge of good behaviour. In late 1597, Niall told two of Hugh Roe's enemies, imprisoned in Donegal, that he would join the English if their forces were sent there. From at least 1598, Tyrone had his doubts about the sincerity of Niall’s loyalty.
In 1597 and 1598, Niall was sent by Hugh Roe on military expeditions into Connacht. Hugh Roe left Niall in charge of the siege of Collooney castle in July 1599. However, Niall was alienated when Hugh Roe deprived him of his castle of Lifford, which he had inherited from his father Conn.

## Defection
### Arrival of Docwra

In May 1600, English-born soldier Sir Henry Docwra established an English garrison in Derry. Docwra had a policy of fostering divisions in the leading Irish clans in order to win Gaelic support for the Crown. Niall's grievances were well-known and Docwra had special instructions to win him over. He believed that Niall's resentment against Hugh Roe was a political asset which the English should exploit to its fullest extent. Shortly after Docwra's arrival at Derry, he opened up secret communications with Niall. By August, Niall had sent through his list of demands, the principal of which was to rule Tyrconnell in the same manner as his grandfather Calvagh. Docwra promised that, if Niall would do service against Hugh Roe, he would obtain for him a grant of the whole of Tyrconnell. Niall accepted the offer, and the bargain was ratified by the Lord Deputy and council.
In September 1600, Hugh Roe left Ulster for a raid in Clare, leaving Niall in charge of besieging Docwra at Derry. Niall and his followers murdered Niall's uncle Neachtan O’Donnell in a drunken rage. Neachtan was "a man of great authority with [Hugh Roe] and all his country". Fearing the return and revenge of Hugh Roe, Niall quickly defected to the English on October 3.
Additionally, Hugh Roe's supporters had become aware of Niall's disloyalty and he was rushed into leaving for Derry before he was ready. Niall brought over 200 men with him to Docwra, but would have brought more if not for the shortness of time. His brothers Hugh Boy, Conn Oge and Donal also defected with him.
Niall was one of many other disgruntled Gaelic Irish noblemen who would defect on Docwra's promises, including Arthur O'Neill and Cahir O'Doherty.

### Battle of Lifford

Accompanied by English forces, Niall marched to Lifford, which had been left in the control of Hugh Roe's tanist and younger brother Rory. The loyalists successfully stormed and took control of Lifford on 9 October. Hugh Roe was shocked at Niall's betrayal and rushed back to Ulster to besiege the loyalist forces. Despite attempts from Rory and Hugh Roe to retake Lifford, they were unsuccessful.
From Lifford, Niall and his brothers, Hugh, Donnell, and Con, made several raids into Tyrone, and captured Newtown from the O'Neills. Men, women and children were killed, and 500 cows were pillaged and taken back to Lifford.
This climaxed in the Battle of Lifford on 24 October. During the battle, Niall fatally wounded Rory's younger brother Manus. Rory and Niall engaged in single combat, though both men were lucky to leave the battle alive. Docwra was pleased that the feud between Niall and Hugh Roe had been exacerbated, as it pushed Niall further into opposition with the confederacy. By December 1600, Hugh Roe had put a price of £300 on Niall's head.
Apparently Niall later made efforts to return to the Irish confederacy, but this was obviously difficult due to his murder of Manus.

### Military skill

Niall Garve O'Donnell was unrivalled in his use of Ireland's terrain as part of guerilla warfare. This skill was a key factor that increased the prowess of English troops in north-west Ulster. His team of spies and his skill in navigating Irish terrain were valuable tools to the English. He also provided intel on Hugh Roe's tactics. With Niall as an ally, the English could mobilise across Tyrconnell.
By Docwra's admission, Niall's service was crucial. After the war, he wrote "I must confess a truth, all by the help and advice of Neal Garbh and his followers, and the other Irish that came in with Sir Arthur O'Neale, without whose intelligence and guidance little or nothing could have been done of ourselves".

### Quarrels with the English

In December 1600, Niall travelled to Dublin to meet Lord Deputy Mountjoy. On 18 March 1601, Niall was granted a custodium of Tyrconnell (excepting Ballyshannon and the fishery of the Erne). This recognised him as the O'Donnell clan chief. But to Niall's dismay, fellow loyalist Cahir O'Doherty was established by Docwra in the lordship of Inishowen, a part of Tyrconnell. Mountjoy was willing to establish Niall in the lordship of Tyrconnell, but wouldn't permit him to enforce his supremacy over O'Doherty. Niall was unwilling to give away any of Tyrconnell, and regarded Mountjoy's decision as an infringement of his rights. Niall's goal was to rule Tyrconnell in its entirety, in the style of a traditional Gaelic chief. In contrast, the English wanted Tyrconnell to be subsumed under the Kingdom of Ireland, and for Niall to remain under the authority of the Crown. To placate Niall, Docwra gave him control of MacSweeney's country. This was the beginning of a growing resentment between Niall and English authorities. When he returned to Derry in April, his relationship with Docwra was beginning to worsen.

### Further conflict

In April 1601, Hugh Roe unexpectedly marched on Niall, forcing him to temporarily retreat to Derry. On 26 May 1601, upon hearing that Tyrone was near Lifford, Niall put together a small group of both Irish and English and attacked Tyrone's larger army. Niall's forces killed 100 of Tyrone's men, and chased Tyrone for miles.

### Siege of Donegal

In August 1601, Niall led an Anglo-Irish force that captured Donegal. In particular Niall was able to capture Donegal's Franciscan priory Donegal Abbey, which housed a confederate munition store consisting of "a great chamber full of calivers and muskets, a loft full of pikes, and three of powder, containing by estimation two hundred barrels".
Niall's hold over Donegal virtually stopped Hugh Roe from entering Tyrconnell, and a subsequent month-long siege ensued. It came to a head on 26 September (or 19 September) when a gunpowder explosion in the store caused a raging fire in Donegal Abbey. Hugh Roe hurriedly ordered his men to attack, leading to a chaotic engagement amidst the burning abbey. It seemed that Niall would be defeated, but the loyalist forces held out until reinforcements from Docwra arrived, forcing Hugh Roe to retreat. During the battle, 300 of Niall's followers were killed, including his brother Conn Oge, who was buried under fallen stones. It is possible Niall's losses came more from the raging fire rather than enemy attacks.
Around this time, Docwra received "many informations against" Niall, but confessed that Niall that "behaued himselfe deservinglie," and "had many of his men slaine at the siege of Kinsale, and amongst the rest a brother of his owne".
Niall was so unsettled by the siege that, with Docwra's permission, he began negotiating with Hugh Roe. He requested "that in recompense of this service he should be made tánaiste of Tír Chonaill and have the present lordship of all the country between Bearnas Mór and Inishowen and where Niall Garbh’s wife being sister to [Hugh Roe]… that upon this agreement … she was still reserved for Niall to have again". However, Niall's conditions (which included "that [Hugh Roe] and [Niall] should be bound and sworn never to come in sight of one another") were so numerous that Hugh Roe discarded the negotiations.

### Siege of Kinsale

Niall's assistance to the English was a major reason for the weakening of Hugh Roe's forces. By the time Irish forces were marching to Kinsale, Niall and Docwra had essentially conquered Tyrconnell and left Hugh Roe with no home to return to. England's victory at the Siege of Kinsale crushed the Irish confederacy. After the departure of Hugh Roe from Ireland in 1602, Rory was left as acting chief. Rory and his ally Brian O'Rourke lost Ballyshannon to Niall in spring 1602.

## Post-war

By 1602, Niall was in control of Tyrconnell and was effectively the O'Donnell clan chief. In March, he was knighted by Mountjoy. However, that year the rift between Niall and Docwra increased as they argued over pay and the division of plundered goods. By end of the year, Niall refused to help or even meet Docwra. In response, Docwra wrote to Dublin accusing Niall of plotting with Tyrone and Hugh Roe against the crown. Given the animosity between Niall and the confederacy leaders, this was clearly a ploy by Docwra. It is possible that Docwra, not well-regarded as a military strategist, was jealous of the plaudits Niall received for his military assistance. Additionally if Niall was disgraced, his land rights would be retracted by the Crown; this would allow Docwra to obtain a grant to parts of Tyrconnell.
On 25 March 1602, Niall and an English force defended Ballyshannon castle against Rory. With Niall's strong hold over Tyrconnell, Donough McSweeney Banagh submitted to him and the English. In January 1603, Rory submitted to the English. Niall was alarmed and correctly assumed that the English would pit Rory against him in a power struggle for Tyrconnell. Niall responded by seizing Rory's cattle, and he may have even tried to murder Rory.
News of Niall's insubordination reached Mountjoy, who summoned him to Dublin with the apparent intention of granting him a patent of Tyrconnell. Niall disobeyed the summons as he had received news of Hugh Roe's death in Spain, which had occurred on 30 August 1602. In April 1603, Niall tried to seize the chieftainship and was "inaugurated" as O'Donnell clan chief in Kilmacrennan with the customary ceremonies. However, he did not have the full required support of the derbfine (electoral kinship group). His chieftainship was repudiated by Hugh Roe's surviving family, especially Rory.
In 1603, Caffar Óg O’Donnell and Mulmurry McSweeney Doe went to Tyrconnell, "with their people and cattle, to wage war with Niall Garbh and the English". Shortly afterwards Caffar Óg was captured by Niall.
Mountjoy initially treated Niall with good faith but was now weary of his insubordinate behaviour; he ordered Niall's arrest. Docwra arrested Niall, but allowed him to go to Dublin to plead his cause with Mountjoy in person. According to O'Sullivan Beare: "[Niall] had himself inaugurated O'Donnell by O'Ferrall, and for so doing was imprisoned in Derry by the English, who hate the Irish titles and wished to abolish such inaugurations. [Niall] escaped to a thick wood where he assembled his forces and party. [Rory] and Dowcra, joining their forces, stripped him of his goods and shattered his resources. Hence it came to pass that of his party 4,000 men, women and children died of famine, and himself reduced to poverty fled into England less valued now by the English than [Rory]."
Niall subsequently escaped but was pursued by Rory and Docwra. In their bid to recapture the fugitive, they captured all of Niall's cattle and starved or killed many of his followers. Niall ultimately gave himself up and was allowed to proceed to London "to solicit pardon for his offences, and to obtain the reward for his service and aid to the crown of England." Docwra advised that Niall should be imprisoned or executed, but Niall still had several supporters at court.
At the same time Rory also went to London, where the English Privy Council endeavoured to solve the O'Donnell family quarrel. The council raised Rory to the peerage as 1st Earl of Tyrconnell—effectively the lordship. To Niall, they granted 12,900 acres of land extending from Laght in the parish of Donaghmore to Sheskin-loobanagh in the parish of Croaghonagh. This was the land Niall's family had already owned prior to the outbreak of war. This decision failed to satisfy either Niall or Rory.
Niall shortly afterwards complained that he was debarred from the full enjoyment of the lands assigned to him. He smugly refused to formally take out the patent for the lands granted to him (though he retained the land in practice). For the next few years, Niall continued his vendetta with Tyrone and Rory, and engaged with them in land disputes.

## Later life

In 1605 Lord Deputy Arthur Chichester tried without success to reconcile their differences. In 1607 Chichester promised Niall lordship of Inishowen.
In March 1607, Niall served against Cathbhar Oge O'Donnell, and was reputed to have "got a blow in the service which he will hardly recover of long time, if he escape with his life".
In September 1607, due to increasing hostility towards former confederacy members, Rory and Tyrone left Ireland for continental Europe. This restored Niall's hopes that he could claim the lordship of Tyrconnell. However, his claims were ignored, and he is said to have refused the title of Baron of Lifford. By 1608 he was heavily in debt.

### O'Doherty's rebellion

In early 1608, it appears Niall encouraged Cahir O'Doherty to instigate a rebellion against the Crown. O'Doherty was a Gaelic Irish nobleman who had similarly defected to Docwra's forces in 1600. However, he had become angered at his poor treatment by Sir George Paulet, Docwra's successor as governor of Derry.
O'Doherty burnt Derry on 19 April 1608, but Niall stayed aloof from the rebellion. He clearly hoped to be awarded O'Doherty's lands of Inishowen in the event of a failed rebellion, as promised by Chichester. Niall rejected meetings with the English, starting bargaining with them over the price of his assistance, and demanded for him to be finally recognised as the rightful Lord of Tyrconnell. When English forces arrived in late May 1608, Niall pledged his assistance in catching O'Doherty. It appears however that he maintained correspondence with O'Doherty and warned him of his enemies' movements. The English quickly grew suspicious.
Niall was charged by his mother-in-law Iníon Dubh with having instigated O'Doherty's rebellion. Niall protested his loyalty, but after some delay, and under protection from Treasurer Thomas Ridgeway, Niall and his two brothers (Hugh and Donal) surrendered on 14 June. They were committed, on a charge of corresponding clandestinely with O'Doherty, "to the custody of the captain of the Tramontane" to be conveyed immediately to Dublin. Niall was charged on six counts of treason and imprisoned in Dublin Castle. Subsequently, many of O'Doherty's supporters (including his wife) implicated Niall in the rebellion.

### Trial

The Attorney-General for Ireland, Sir John Davies, found little difficulty in accumulating proof of Niall's correspondence with O'Doherty, but the question arose whether his guilt had not been condoned by his protection. He was not brought to trial until June 1609. During this interval, Niall and his brothers made numerous unsuccessful attempts to escape their confinement.
On 1 July Niall was examined before the council and committed to the castle. On Friday, midsummer-eve, he was put on his trial in the king's bench. Despite considerable pressure from the government to convict Niall, the Donegal jury feared retribution from Niall's supporters and threats of excommunication from the catholic clergy. After three days, Davies realised that the jury would acquit Niall. "Pretending that he had more evidence to give for the king, but that he found the jury so weak with long fasting that they were not able to attend the service," Davies discharged them before they gave their verdict. According to Clavin, these proceedings were "brazenly illegal".
Davies suggested trial by a Middlesex jury, as in the case of Sir Brian O'Rourke. Chichester would have liberated the brothers from prison on giving security.

### Death

In October 1609, Niall and his son Naghtan were committed to the Tower of London. This is where Niall remained until his death in 1626, aged 57.

## Personality

Of the commanders working for the Crown, Niall was one of the most zealous and aggressive in attacking Irish civilians during his raids. He is described by Lughaidh Ó Cléirigh, Hugh Roe's biographer, as "a violent man, hasty, austere, since he was spiteful, vindictive, with the venom of a serpent, with the impetuosity of a lion. He was a hero in valour, and brave." Docwra wrote that Niall was "proud, valiant, miserable, tyrannous, unnecessarily covetous, without any knowledge of God, or almost any civility". Historian Paul Walsh points out that Docwra would have described any Irishman of his time in this manner, and that because of Niall's betrayal of both Gaelic Ireland and the Crown, both Irish and English contemporary sources would be somewhat biased again him.
Philip O'Sullivan Beare called Niall "a man of great spirit and daring, skilled in military matters". He references that, despite working for the Protestant Crown, Niall "always retained the Catholic faith and kept aloof from heretical rites." Indeed, a condition of Niall assisting Docwra was a guarantee of liberty of conscience for himself and his followers.
According to Clavin, Niall "displayed a childlike cunning, even naivety" in his dealings with the English. He was "first and foremost a warrior,... unsuited to the role of a landlord". Robert Dunlop described him as "certainly a most unfortunate and badly used man".
It is known that Niall spoke broken English, and required Willis to translate for him.
A bardic poet wrote a poem on Niall's ambition to become Lord of Tyrconnell:
| Original Irish | English translation |
| Do ba neimní re Niall Garbh crínad a alt df[h]iaclaib feól-arm go tarrachtain tíre a sean df[h]ath-bertaibh gríbhe Gaoidheal. | Niall Garbh little cared if his limbs were chopped by the teeth of weapons, provided only he saved his forbears’ land with skilful deeds of a chief of the Gaedhil. |

## Family

Niall Garve married his first cousin once-removed Nuala O'Donnell, sister of Hugh Roe and Rory. When Nuala heard of her husband's defection, she ended their marriage and deserted him. Niall had at least two children: Naghtan and Manus. Historians John O'Donovan and Eunan O'Donnell claim that they were Nuala's children. Nuala had a daughter named Grania, though it is unclear whether or not Niall was her father. According to historian George Hill, Naghtan had two younger brothers.
A report by Docwra describes Hugh Roe murdering Niall and Nuala's child in a furious reaction to his betrayal in 1600:
   "O’Donnell hath of late hanged many of good account . . . he dasht owt the brains of Neil Garve’s childe (of [four] yeares olde) againste a post, beinge in the mother’s custody, his owne naturall sister."
Docwra's biographer John McGurk acknowledges that there is an uncertainty as to the report's truthfulness. McGurk points out that Docwra's "blunt" personality would indicate that he reported current affairs accurately, though it is unclear where Docwra received this intelligence. If this report is true, it does not explain why Nuala maintained her loyalty to Hugh Roe and Rory. McGurk also acknowledges that infanticide was a feature of warfare in the early modern period. Historian Hiram Morgan notes that since this is a contemporary account, it should not be dismissed out of hand. Regardless, such a child would have been born around 1596.
Following Hugh Roe's death in 1602, Nuala joined the household of his successor Rory. When Rory fled to Rome in 1607, Nuala accompanied him, taking her little daughter Grania with her. In 1617, Grania came to England to petition for some provision being made for herself out of her father's estate.
In 1602, Niall contemplated a marriage with the widow of Sir Arthur O'Neill, Turlough Luineach O'Neill's son. It is unknown whether he married her, but according to Paul Walsh, it is unlikely that Niall remained without a partner until his arrest in 1608.
Historian Eunan O'Donnell gives Naghtan's lifespan as 1591–1624. When Niall defected, he gave Naghtan to Docwra as a hostage as a surety, which would mean that Nuala was Naghtan's mother. Naghtan was described as "a boy of an active spirit, and yet much inclined to his book". He studied at St John's College, Oxford, at the charge of the Earl of Devonshire. In Alumni Oxonienses he is given the name Hector. He was then sent to Trinity College Dublin, whence he was transferred to Dublin Castle. He was committed to the Tower of London with his father in October 1609, and died in 1640 during his imprisonment.
Manus was Niall's eldest surviving son. He served as a colonel under Owen Roe O'Neill in the Irish Confederate Wars. He died at the Battle of Benburb on 5 June 1646. The O'Donel baronets of Newport House in County Mayo are descended from Manus's son Rory.

## Legacy

According to historian David Finnegan, Irish nationalist historians represent Niall as having betrayed Gaelic Ireland. He has been compared to Dermot MacMurrough, the medieval King of Leinster who incited the Anglo-Norman invasion of Ireland.