Following the latter's defeat and overthrow by Edward I, King of England, Alasdair Óg aligned his kindred with the English in an attempt to contend with Clann Dubhghaill.

The Clann Domhnaill succession is uncertain following this date, as several men appear on record accorded the territorial designation "of Islay", a style that corresponded to the lordship of the Isles.

[29] Aonghus Mór, and his Clann Somhairle kinsman Eóghan Mac Dubhghaill, evidently named their eldest sons after the kings of Scotland.

[37] The independence of the Islesmen, and the lurking threat of their nominal overlord, the formidable Hákon Hákonarson, King of Norway, constituted a constant source of concern for the Scottish Crown.

When mediation came to nought, Alexander III evidently orchestrated an invasion into the Isles as means to openly challenge his Norwegian counterpart's authority.

[41] As a result of his failure to break Scottish power, Alexander III seized the initiative the following year, and oversaw a series of invasions into the Isles and northern Scotland.

[43] In the wake of the Norwegian withdrawal, and the violent extension of Scottish royal authority into the Isles, Aonghus Mór had no choice but to submit to the Scots.

[69] The bond's Anglo-Irish cosignatories may have sought maritime support from Clann Domhnaill,[70] and it is possible that Aonghus Mór contributed to the earl's operation.

Forced from its Scottish homeland, Clann Suibhne evidently found a safe haven in Tír Chonaill on account of an alliance forged with Domhnall Óg.

[65][note 8] By the death of Alexander III, the Clann Domhnaill holdings seem to have included Kintyre, Islay, southern Jura, and perhaps Colonsay and Oronsay.

The infighting appears to have stemmed from Alasdair Óg's marriage to an apparent member of Clann Dubhghaill, and seems to have concerned a dispute over this woman's territorial claims.

[96] In the north-west, William II, Earl of Ross was made Sheriff of Skye, with a jurisdiction that appears to correspond to the territories formerly held by the Crovan dynasty before 1266.

[98][note 9] Despite the king's intentions of increased authority, stability, and peace, his new sheriffs seem to have used their elevated positions to exploit royal power against their own local rivals.

[107][note 10] Alasdair Óg's undated renewal of his father's grant of St Ciarán seems to be evidence that Aonghus Mór had been succeeded by the date of its issue.

[114] As such, Alasdair Óg was given jurisdiction over an area formerly under the authority of the steward,[115] a man who had briefly taken up arms against the English in 1296 but quickly capitulated when resistance proved futile.

It is also possible that the English orchestrated this delegation of authority in the context of adopting a divide-and-rule policy in the region as a way to offset Alasdair Óg's influence.

[121] In an undated letter that appears to date to about the summer of 1296, Alasdair Óg reported to the English king that he had secured possession of the steward's lands in Kintyre, and was on verge of taking control of a particular castle.

At the end of the letter, Alasdair Óg related that he was in the midst of organising a retaliatory operation, and implored upon Edward to instruct the other noblemen of Argyll and Ross to aid him in his struggle against the king's enemies.

[147] In the second letter, Alasdair Óg again appealed to the English Crown, complaining that he faced a united front from Donnchadh, Lachlann, Ruaidhrí, and the Comyns.

Alasdair Óg further related a specific expedition in which he pursued his opponents to the Comyn stronghold of Inverlochy Castle[148]—the principal fortress in Lochaber[149]—where he was unable to capture—but nevertheless destroyed—two massive galleys which he described as the largest warships in the Western Isles.

[148][note 13] Alasdair Óg also reported that, on account of the steward's disloyalty to the king, he seized control of the castle and barony of "Glasrog" (probably Glassary).

[148] Alasdair Óg's dispatches seem to show that Lachlann and Ruaidhrí were focused upon seizing control of Skye and Lewis and Harris from the absentee Earl of Ross.

[158] Whether the Clann Somhairle kin-strife continued after Alasdair Mac Dubhghaill's May release is uncertain, although it would seem highly probable given the remarkable animosity between the concerned parties.

[159] If Edward did not intend for this liberated clan chief to reign in his family, another possibility is that his release was instead envisaged as a counterbalance to Alasdair Óg's power, to ensure that the latter was kept in check.

[161] Nevertheless, although Alasdair Óg was ostensibly working on the king's behalf, it is evident that local rivalries and self-interest laid behind the region's political alignments, not anti-Englishness.

[177] The latter's death took place after his recognition as bailiff of Loch Awe and Ardscotnish by Edward in September 1296, suggesting that he too was employed by the English against Clann Dubhghaill.

[178][note 17] Accordingly, both Alasdair Óg and Cailéan Mór appear to have succumbed to Clann Dubhghaill whilst attempting to extend Edward's authority into Argyll and bring the clan to heel.

[194][note 22] Further evidence of a contentious family succession may be the record of a certain Alasdair of the Isles,[199] who received a grant of the former Clann Dubhghaill islands of Mull and Tiree from Robert I.

[241] In fact, before the end of Robert I's reign, this Eóin appears to have administered Islay on behalf of the Scottish Crown,[242] and eventually came to style himself Lord of the Isles.

At one point, Alasdair Óg is said to have been besieged by the king within Castle Sween, where he was captured and later died there as a prisoner, however, the better reasoned view is that he was always loyal to the Bruces.