When the castle was built is unknown, but probably in the thirteenth century, and its situation is perhaps doubtful, but it is more than likely to have been on the site of the old Roman fort at the Peel. It belonged to the Comyns, and probably was built by them, and destroyed in the time of Bruce.

The Romans no doubt selected the Peel as the strongest place for a fortress; and it would recommend itself to the Comyns as equally serviceable for theirs. Mr. Dairymple Duncan suggests to us a potent reason which we regard as conclusive of our theory. The name Peel is an old purely Scottish word signifying “a place of strength,” and Comyn’s castle has given it that name—not the Roman fort, which would be in ruins long previous to that time, if there were any vestige of building above ground at all, after the lapse of about a thousand years.

The piece of ground referred to in Lord Wigton’s charter to the town as “Cumynschach” or Comyn's Haugh and which is near the Peel is also corroborative evidence.

A curious circumstance occurred in connection with the castle, and the building of Glasgow Cathedral.

The Lord of Luss granted to the chapter of the cathedral the privilege of cutting timber on Loch Lomond for the building, and Bishop Robert Wishart—who was consecrated in 1272—had charge of the arrangements.

He was called “the warlike bishop” and was an ardent patriot He stoutly contested the claim of Edward I. to the kingdom of Scotland; was a partisan of Wallace; granted absolution to Bruce from the sin of stabbing the treacherous Comyn in the church of Dumfries; and was afterwards his ardent supporter.

The castle of Kirkintilloch was in possession of the English and was being besieged by the Scots; and “the warlike Bishop” — whose patriotic spirit for the time overcame his ecclesiastical tendencies—had no scruple in using part of the timber intended for the cathedral in making catapults or engines of war for the siege of Kirkintilloch castle.

For this, he was afterwards bitterly reproached by King Edward, who also wrote to the pope complaining of the bishop assisting the Scotch against him—and the pope wrote thus to the bishop on 13th August, 1302: “I have heard with astonishment that you, as a rock of offence and a stone of stumbling, have been the prime instigator and promoter of the fatal disputes between the Scottish nation and Edward King of England, my dearly beloved son in Christ, to the displeasing of the Divine Majesty, to the hazard of your own honour and salvation, and to the inexpressible detriment of the kingdom of Scotland. If these things are so, you have rendered yourself odious to God and man. It befits you to repent, and by your most earnest endeavours after peace to strive to obtain forgiveness.” To which the bishop answered that, “It is better to fight for Robert the Bruce in Scotland, than against the Saracens in the Holy Land.”

The good Bishop fought on, until, when defending Cupar against the English, he was taken prisoner in 1306, and was not liberated till after the Battle of Bannockburn in 1314— he died in 1316.