l policy by his marriage with Joan of Bar, Edward's
grand-daughter. In the same way Edward's young nephew, Thomas of
Lancaster, ruled over the three earldoms of Lancaster, Derby, and
Leicester, and by his marriage to the daughter and heiress of Henry
Lacy, was destined to add to his immense estates the additional
earldoms of Lincoln and Salisbury. Edward of Carnarvon was learning the
art of government in Wales, Cheshire, and Ponthieu. The policy of
concentrating the higher baronial dignities in the royal family was no
novelty, but Edward carried it out more systematically and successfully
than any of his predecessors. He reaped the immediate advantages of his
dexterity in the extinction of baronial opposition and in the zeal of
the baronial levies against the Scots during the concluding years of
his reign. Yet the later history of the Middle Ages bears witness to
the grievous dangers to the wielder of the royal power which lurked
beneath a system so attractive in appearance.

The truce with the Scots ended in November, 1302, and Edward despatched
a strong force to the north under John Segrave. On February 24, 1303,
Segrave, attacked unexpectedly by the enemy at Roslin, near Edinburgh,
suffered a severe defeat. The conclusion of the treaty of Paris gave
Edward the opportunity for avenging the disaster. He summoned his
levies to assemble at Roxburgh for Whitsuntide and, a fortnight before
that time, appeared in person in Tweeddale. After seven weary years of
waiting and failure, he was at last in a position to wear down the
obstinate Scots by the same systematic and deliberate policy that had
won for him the principality of Wales. The invasion of Scotland was
henceforth to continue as long as the Scottish resistance. Adequate
resources were procured to enable the royal armies to hold the field,
and a politic negotiation with the foreign merchants resulted in a
_carta mercatoria_ by which additional customs were imposed upon
English exports. These imposts, known as the "new and small customs,"
as opposed to the "old and great customs" established in 1275, were not
sanctioned by parliamentary grant: but for the moment they provoked no
opposition. Thus Edward was equipped both with men and money for his
undertaking. At last the true conquest of Scotland began.

No attempt was made in the Lothians to stop Edward's advance, but the
Scots, under the regent, John Comyn of Badenoch, made a vigorous effort
to hold the line of the