Scotland consolidates authority in the maritime region between the Lennox and Cowal, and along the eastern coast of the Firth of Clyde towards Galloway, in the early 1160s.
David may well have begun the infeftment and settlement of this coastal district decades earlier, in order to counter the sea borne threat that the rulers of Argyll had posed during the dynastic challenges of the 1130s.
Some of the greatest Scottish magnates have taken root in the region by the 1160s, and it is not impossible that some of them may have begun to extend their influence into southern Argyll and the Islands of the Clyde.
The catalyst for Somerled's invasion may therefore be the encroachment of Scottish influence into his own sphere of hegemony.
The target of his invasion appears to have been Renfrew, the center of the family of Walter FitzAlan, Steward of Scotland, and Somerled's forces may well have engaged those of Walter—possibly even led by the steward himself.
When the Anarchy took hold in England and civil war between Empress Matilda and Stephen, Walter FitzAllan, the third son of a Breton knight, had rallied to the support of the Empress.
When her cause was lost, Walter had befriended David I who was an uncle of Matilda, and became David's dapifer or Steward.
Accompanied by his brother Simon, Walter had come to Scotland about 1136 and fought for Scotland at the Battle of the Standard at Northallerton in 1138 under the command of David I's son, Prince Henry.
Subsequently he had been appointed Steward of Scotland by King David I; in 1157 the appointment as Steward had been confirmed as a hereditary office.
In return for the service of five knights, David had also granted him what will eventually comprise Renfrewshire: the lands of Paisley, Pollok, Cathcart, and Ayrshire; this grant had been reconfirmed in a charter in 1157 from Malcolm IV.
