Uilleam I of Ross was the first successor of
Ferchar mac an tSagairt, as
Mormaer of
Ross, with his comital dates traditionally given as
1251-1274.
Uilleam appears as early as
1232, witnessing a charter as the son of Ferchar. He was definitely Mormaer by
1258, but the traditional date is
1251. Uilleam played a pioneering role in the Scottish reconquest of the formally
Norwegian Hebrides. Indeed, in many ways, he may be regarded as the instigator of Scottish aggression.
Hakon's Saga tells us that in Norway:
"
In the previous summer [i.e. that of 1262]
, letters came east from the Hebrides ... and they brought forward much about the dispeace that the Earl of Ross ... and other Scots, had made in the Hebrides, when they went out to Skye, and burned towns and churches, and slew very many men and women ... They said that the Scottish king intended to lay under himself all the Hebrides."
1
Uilleam's attacks on Norwegian possessions earned him the ire of King
Håkon IV, who planned an expedition against him. However, Uilleam escaped this expedition. He was probably rewarded with
Skye and
Lewis after the Scottish reconquest of the Hebrides, a reward secured when the conquests were ratified by the
Treaty of Perth in
1267.
He married Johanna
Comyn, the daughter of
William Comyn, jure uxoris Earl of Buchan, by whom he fathered his successor
Uilleam.2 He died, probably in
1274. 
