The wife of David, Matilda, widow of Simon de St Liz, was heiress of
Waltheof, sometime the Conqueror's Earl in Northumberland; and to gain,
through that connection, Northumberland for himself was the chief aim of
David's foreign policy,--an aim fertile in contentions.

We have not space to disentangle the intricacies of David's first great
domestic struggles; briefly, there was eternal dispeace caused by the
Celts, headed by claimants to the throne, the MacHeths, representing the
rights of Lulach, the ward of Macbeth. {20} In 1130 the Celts were
defeated, and their leader, Angus, Earl of Moray, fell in fight near the
North Esk in Forfarshire. His brother, Malcolm, by aid of David's Anglo-
Norman friends, was taken and imprisoned in Roxburgh Castle. The result
of this rising was that David declared the great and ancient Celtic
Earldom of Moray--the home of his dynastic Celtic rivals--forfeit to the
Crown. He planted the region with English, Anglo-Norman, and Lowland
landholders, a great step in the anglicisation of his kingdom.
Thereafter, for several centuries, the strength of the Celts lay in the
west in Moidart, Knoydart, Morar, Mamore, Lochaber, and Kintyre, and in
the western islands, which fell into the hands of "the sons of Somerled,"
the Macdonalds.

In 1135-1136, on the death of Henry I., David, backing his own niece,
Matilda, as Queen of England in opposition to Stephen, crossed the Border
in arms, but was bought off. His son Henry received the Honour of
Huntingdom, with the Castle of Carlisle, and a vague promise of
consideration of his claim to Northumberland. In 1138, after a disturbed
interval, David led the whole force of his realm, from Orkney to
Galloway, into Yorkshire. His Anglo-Norman friends, the Balliols and
Bruces, with the Archbishop of York, now opposed him and his son Prince