After the death of King Henry I of England, King David I supported the claims of Henry’s daughter and his own niece (Matilda) to the throne of England against her cousin Stephen of Blois. David led a Scottish army into northern Yorkshire in January 1138. King Stephen moved north with his army but both armies avoided each other until late July. The Scottish army was defeated at the ‘Battle of the Standard’ in August 1138. David’s army retreated to Carlisle but his men continued to occupy Cumberland as well as much of Northumbria. In April 1139 the second treaty of Durham was settled. David’s young son Henry was given the earldom of Northumberland and was restored to the English earldom of Huntingdon. As part of the treaty, King Stephen of England recognized Scotland as an independent kingdom including Northumbria.

The leader of Atholl at this time (1115-1152) was Henry, 1st celtic earl of Atholl. This Henry was the son of Melmare, younger brother of Malcolm Canmore. He was first cousin to both King Alexander I and King David I. Being a close relative, he played an active part in public affairs and would have been part of the Scottish army with his retainers.

Henry, 3rd celtic earl of Atholl had a second son named Conan. On Henry’s death, Conan did not succeed to the earldom, but did inherit vast lands from his father. Conan, is the founder of the "de Atholia" line from which our clan chiefs descend. Four generations later Conan’s great-great-grandson Duncan became our first recognized clan chief. Conan’s original lands in Glenerochie formed the core of what became our expanded clan lands.

With the return of Holy Roman Empress Matilda and her supporters to southern England in late 1139, the English civil war with King Stephen was renewed. David took advantage of this strife to increase his domination over northern England. David’s capture of the silver mines at Alston and the established English mint at Carlisle in 1136 enabled him to begin minting Scotland’s first silver coinage (sterling silver pennies) and later established additional mints at Edinburgh, Berwick and Roxburgh.

King David I was one of medieval Scotland’s greatest monastic patrons. As such, he was able to convince the pope that as an independent kingdom, the Scottish church should be freed from the control of the archdiocese of York. He established nine bishoprics at St. Andrews, Aberdeen, Brechin, Caithness, Dunblane, Dunkeld, Glasgow, Ross and Whithorn. He was later canonized as a Saint for his work in establishing fifteen religious houses throughout Scotland, including abbeys at Selkirk, Kelso, Holyrood (now Holyrood Palace in Edinburgh), and Melrose.

References:
Cowan, Samuel, "Three Celtic Earldoms", 1909, pp 11-15.
Donaldson, Gordon, "Scottish Kings", 1977, pp 9-16.
Paton, Sir Noel, "The Descendants of Conan of Glenerochie", 1873, pp 3-4.
Ross, David, "Scotland, History of a Nation", 2004, pp 61-68.