The Treaty required William to swear that Scotland would thereafter be subordinate to the English crown. English soldiers were also to occupy several key Scottish castles, and Scotland would be heavily taxed to pay for their upkeep. During the next 15 years, William was forced to observe Henry's overlordship, and to obtain permission from the English crown before putting down local uprisings.
^The Struggle for Mastery page 226: By the Treaty of Falaise in 1174 William was released, but in return for acknowledging that his kingdom was henceforth a fief held from the king of England. Henry was also to receive homage and fealty from the earls and barons and other men of "the land of the king". All of this was to be guaranteed though the surrender by King William of the castles of Roxburgh, Berwick, Jedburgh, Edinburgh, and Sterling.
^Andrew Lang, A History of Scotland from the Roman Occupation, 1900. p. 113.
^The Struggle for Mastery: With Richard in a hurry, a bargain was quickly struck. William gave £6,666 to recover the castles of Berwick and Roxburgh and free his realm from the subjection to England imposed in 1174.