Soule/Soulis was accepted by CDSNA as a sept in June 1984.
This surname apparently is a location name. A certain John of Soules was a companion of both Edward Bruce (brother to King Robert 1) and “The Good” Sir James. Fraser relates,
About the beginning of August, Edward Bruce, ["The Good" Sir James] Douglas, and John of Soules, at the head of a large army, made a raid into England, near Berwick, and passed through Northumberland and Durham to the river Tees, even crossing it and penetrating to the town of Richmond. Their course was marked by fire and slaughter, the inhabitants of the invaded districts fleeing to the woods and castles for refuge, or with their cattle and sheep being driven before the Scottish soldiers. [Fraser. v1, p 437]
John of Soules appears to have been a cousin of the Bruce family. After the ascension of Robert Bruce as King of Scotland in 1306, another Soules, William de Soules was found to be a conspirator in an attempt to usurp the crown from the Bruce. As Fraser states,
The Soulis conspiracy was the cause of another estate being conferred upon the Lord of Douglas, that of the extensive barony of Watstirker or Westerkirk in Eskdale. William de Soulis, who had but recently been received into favour by Bruce, and on account of his connection with the blood- royal, was created high butler of Scotland, formed a plot to assassinate Bruce and others, with the object of setting himself upon the throne, as the lineal descendant of the illegitimate daughter of King Alexander the Second, who had married Alan Uurward. The conspiracy was revealed by the Countess of Strathern, and after being tried and condemned by the Parliament held at Scone in August 1320, popularly called the "Black Parliament," Soulis and his accomplices were executed, and their lands forfeited to the crown. [Fraser. v1, p 474]
The lands of John of Soules were afterwards granted to Sir James Douglas by King Robert Bruce.
13. Charter by King Robert the Bruce to James, Lord of Douglas, knight, for his homage and service, of the half of the whole barony of Watstyrker, in Eskdale, with the pertinents, which belonged to the late William of Soules, knight, and which he forfeited to the King : To be held by the said James and his heirs, of the King and his heirs, in fee and heritage, with fishings, fowlings, and huntings, etc., thereof ; rendering therefore the service used and wont to be rendered for the said land in the time of Alexander the Third. Berwick-on-Tweed, 20th April , [Fraser. v3, p 27]
The CDSNA newsletter, Dubh Ghlase [vol XII, 4, Jan/Feb 1987] printed the following information presented by Authur L. Douglas regarding the inclusion of Soule/Soulis as a sept of Douglas.
“This family were to be found along the Scottish Borderlands of Liddedale, Selkirkshire, and Roxburghshire up until the 14th century. They have been known to have fought alongside Robert ‘The Bruce’ and Sir James Douglas during the Wars of Independence and acquitted themselves with valour. However, they were never a large family at that period of time, and when William de Soulis was the Constable of Hermitage Castle during the 13th or 14th century, he was regarded as a tyrant towards the peasantry who were resident on his lands, and was believed to have kidnapped the children of the farmers in the surrounding countryside.
Such was the outcry against him that the people of that area charged him with being in league with the Devil and of witchcraft. They petitioned the King, who, being sick of hearing about the troubles along the Borderlands, told them to do what they would with William de Soulis, whereupon, the farmers and peasantry joined forces and storming the Castle took William de Soulis prisoner. The King relenting his former orders, sent a messenger to tell the people to let William de Soulis go free, but, the messenger arrived too late and the people, acting on the words of a Border Wizard, or Wise Man, had wrapped William de Soulis in a sheet of lead and plunged him into a boiling cauldron. To this day the stones on which the cauldron stood can still be seen at Nine-Stone-Rig near the Castle.
The Doulgases later took over the Castle of Hermitage and in consequence of the family’s tenure, the de Soulis family, with all of their variations of spelling, can justifiably claim to be a Sept of the Douglases, for they are not large enough, in Scotland, or strong enough to be classified as a separate group or family. Man of the Soulis family moved across the border into Northumberland where they prospered and multiplied and it is there that many of this family may be found today.”
Douglas, Arthur L. "Soule and Soulis." Dubh Ghlase XII.4 (1987). Print.
Fraser, William. The Douglas Book: In Four Volumes. Burlington, Ont: TannerRitchie Pub. in collaboration with the Library and Information Services of the University of St. Andrews, 2005. Internet resource.