The freemen who were armed under this Assize had little occasion to use their weapons so long as King Henry lived. Within the four seas of Britain there was almost unbroken peace till the end of his reign. The treaty with Scotland was ratified by the public homage of William the Lion to Henry and his son at York on August 10, 1175;[887] and thenceforth Henry’s sole trouble from that quarter was the necessity of arbitrating between William and his unruly vassals in Galloway,[888] and of advising him in his ecclesiastical difficulties with the Roman see. The western border of England was less secure than the northern; yet even in Wales the authority of the English Crown had made a considerable advance since Henry’s accession. His first Welsh war, directed against the princes of North Wales in 1157, had little practical result. A second expedition marched in 1163 against Rees Ap-Griffith, prince of South Wales, and a lucky incident at the outset insured its success. Directly in the king’s line of march from Shrewsbury into South Wales, between Wenlock and Newport, there ran a streamlet called Pencarn--a mountain-torrent passable only at certain points. One of these was an ancient ford concerning which a prophecy attributed to the enchanter Merlin declared: “When ye shall see a strong man with a freckled face rush in upon the Britons, if he cross the ford of Pencarn, then know ye that the might of Cambria shall perish.” The Welsh guarded this ford with the utmost care to prevent Henry from crossing it; he, ignorant of the prophecy, sent his troops over by another passage, and was about to follow them himself, when a loud blast from their trumpets on the opposite bank caused his horse to rear so violently that he was obliged to turn away and seek a means of crossing elsewhere. He found it at the fatal spot, and as the Welsh saw him dash through the stream their hearts sank in despair.[889] He marched unopposed from one end of South Wales to the other, through Glamorgan and Carmarthen as far as Pencader;[890] here Rees made his submission;[891] and Rees himself, Owen of North Wales, and several other Welsh princes appeared and swore allegiance to King Henry and his heir in that famous council of Woodstock where the first quarrel arose between Henry and Thomas of Canterbury.[892] [887] _Gesta Hen._ (as above), pp. 94–96. Rog. Howden (Stubbs), vol. ii. p. 79. Cf. Will. Newb., l. ii. c. 38 (Howlett, vol. i. p. 198). [888] On the Galloway affair see _Gesta Hen._ (Stubbs), vol. i. pp. 67, 68, 79, 80, 99, 126, 313, 336, 339, 348, 349; Rog. Howden (Stubbs), vol. ii. pp. 63, 69, 105, 299, 309. [889] Gir. Cambr. _Itin. Kambr._ l. i. c. 6 (Dimock, vol. vi. pp. 62, 63). [890] _Ib._ l. ii. c. 10 (p. 138).