While Church and State in England were thus distressed, the cause of Robert Bruce was making steady progress in Scotland.  It is some measure of the difficulties against which Bruce had to contend that, after six years, he was still by no means master of all that land.  But least of all among the causes which retarded his advance can be placed the armed forces of England.  During six years Edward II.’s one personal expedition had been a complete failure.  A more formidable obstacle in Bruce’s way was the stubborn resistance offered to him by the valour and skill of the small but highly trained garrisons which the wisdom of Edward I. had established in the fortresses of southern and central Scotland.  Each castle took a long time to subdue, and demanded engineering resources and a persistency of effort, which were difficult to obtain from a popular army.  The garrisons co-operated with the Scottish nobles who still adhered to Edward through jealousy of the upstart Bruces and love of feudal independence, rather than by reason of any sympathy with the English cause.  Additional obstacles to Robert’s progress were the hostility of the Church, to which he was still the excommunicated murderer of Comyn; the captivity of so many Scottish prelates and barons in England; the efforts of the pope and the King of France to bring about suspensions of hostilities, and the grievous famines which desolated Scotland no less than southern Britain.  But during these years the King of Scots gradually overcame these difficulties.  His hardest fighting in the field was with rival Scots rather than with the English intruders.  In 1308 he defeated the Comyns of Buchan, and established himself on the ruins of that house in the north-east.  In the same year his brother, Edward Bruce, conquered Galloway, where the Balliol tradition long prevented the domination of the rival family.

Secure from retaliation so long as domestic troubles lasted, the Scots devastated the northern counties of England, whose inhabitants were forced to purchase relief from further attacks by paying large sums of money to the invaders.  Formal truces were more than once made, but they were ill observed, and each violation of an armistice involved some loss to Edward and some gain to Robert.  Meanwhile the garrisons were carefully isolated, and one by one signalled out for attack.  In 1312 Berwick itself was only saved from surprise by the opportune barking of a dog.  In January, 1313, Perth was captured by assault.  Next day Robert slew the leading native burgesses who had adhered to the English, while he permitted the English inhabitants to return freely to their own country.  The whole town was destroyed, since walled towns, like castles, had given the English their chief hold upon the country.