ALBA: Kings of Picts and Scots
The 51st King of Picts, Oengus I, ruled from 729 to 761 (a total of 32 years). There is no disputing the fact that he was noted as a warrior. He killed his Pictish opposition as well as Britons and Scots in great battles. Finally he defeated the Scots of Dalriada and beheaded their King to become the first King of both Picts and Scots for the final twenty years of his reign. It is possibly a lesser known fact that St. Andrew (rather than St. Peter) was "enthroned" as patron of the Picts by King Oengus I. He was probably influenced in the choice of saint by the Columban Christians from the sacred Isle of Iona.
Oengus was followed by his brother Brude/Bridei IV, who ruled for two years. There is, for the first time, reason to believe that the successor, Cinoid, to the Pictish kingship might have had some Scottish blood as well as Pictish, since Dalraida was allowed to become re-established. For a lengthy period there was some confusion and darkness in the list of kings.
Several Pictish kings, including Alpin II, Drust VII, Talorc II, Talorc III MacOengus and Conall, may have reigned briefly before Castantin became the 2nd King of Picts and Scots with a term of 35 years. He was succeeded by his brother Oengus II, who reputedly brought the relics of St. Andrew back to Alba. Oengus II was killed by the Scots, after being forced to divide his army during a battle with the Vikings to the north, when Alpin of the Scots attacked from the south in 834. Some copies of the chronicle name further Kings, such as Drust VIII, Talorc, Uven (killed by Vikings in 839), Uurad, Brude/Bridei V, Kenneth, Brude/Bridei VI and Drust IX (where the lists end).
The battle with the Vikings in 839 claimed not only King Uven and his brother Bran but also the cream of the Pictish warrior class. Thus the stage was set for a claim by a Scot to the Kingship of Picts and Scots under the Pictish rules of succession. There was no "honourable field of battle" in this episode, widely recorded as "Kenneth MacAlpin's Treason", which is reported by F. Lennox Campello as follows. "It is Giraldus Cambresis in De Instructione Principus who recounts how a great banquet was held at Scone, and the Pictish King and his nobles were plied with drinks and became quite drunk. Once the Picts were drunk, the Scots allegedly pulled bolts from the benches, trapping the Picts in concealed earthen hollows under the benches; additionally, the traps were set with sharp blades, such that the falling Picts impaled themselves (the Prophecy of St. Berchan tells that '[MacAlpin] plunged them in the pitted earth, sown with deadly blades'). Trapped and unable to defend themselves, the surviving Picts were then murdered from above and their bodies, clothes and ornaments plundered." In Lion in the North, John Prebble states that seven earls of Dalriada, his kinsmen, were included in the massacre because they might have disputed his claim to Ard-Righ Albainn. [I would question the claim that all of these earls were from Dalriada.]
The power of Kenneth MacAlpin lay in Dalriada to the east and in Fortrenn to the south, but the seeds of northern separatism were sown when a rival kindred, Cenel Loairn, took over in the old Pictish district of Fidach (Moray and Ross). Kings of Scots would soon discover ways to set clan chiefs against one another in order to cement the foundation of their power, but the old Celtic manner of succession to the throne continued to have strong support, as the inhabitants of Pictland were absorbed into the Scottish culture.
Fourteen kings and almost two hundred years later, King Malcolm II was influenced by the Saxon method of succession in the male line of inheritance, but had no male issue. It is suspected that he conspired against the successors of his father, Kenneth II, who reigned from 971 - 995, to gain the throne. In addition to killing King Kenneth III, he removed a few tanists (including the grandson of Boite), who were rivals to his own young grandson, Duncan I, son of Bethoc.
Many abbreviated histories have glossed over the importance of Norse Viking involvement during the transition from Alba to Scotland. Eric Linklater (The Ultimate Viking, Macmillan, 1955, pp.38-40), gives the following account of one Norse saga. "It happened one summer that Sigurd was challenged to a pitched battle by Findlaec, Earl of Moray, ..." and father of Macbeth. "Findlaec, in or about the year 995, was a dangerous enemy, and Sigurd told his mother that if he accepted the challenge the odds against him would be seven to one. To which she replied, 'I would have brought you up in my wool-basket if I had known you expected to live forever! It is fate that governs a man's life, not his own comings and goings; and it is better to die with honour than live in shame.' Then she gave him a raven-banner, finely embroidered, and Sigurd, in a black temper, gathered an army and went to battle at Skitten Mire in Caithness. Three men who carried his banner were killed, but Sigurd was victorious." According to the Ulster Annals and those of Tighernac (translated by O'Cosisser - v.ii. p.267), Malcolm II gave his daughter in marriage to Sigurd "the Stout", Earl/Jarl of Caithness, after the victory over Findlaec.
Duncan I was not the old king in Shakespeare's play, but neither was he a skilled warrior. Furthermore, the Scottish crown is said to have lost nine earldoms (which extended into the heart of Scotland via an alliance and kinship with the Mormaers of Moray) to the Norseman, Thorfinn, Earl of the Orkneys, during Duncan's reign of six years.
After his father Gillacomgain's death, Lulach, probably had had a greater claim to the throne (than Duncan I) through his mother, Gruoch, but he was both youthful and intellectually weak. Gruoch was the daughter of Boedhe (son of Keneth III). Macbeth, son of Findlaech, became Thane of Glamis (Ross and Cromarty) and later Thane of Cawdor (Moray), and he succeeded to the title of Mormaer of Moray and Ross through his own right as tanist in the royal line. When Macbeth married Gruoch, the widow of former Mormaer Gillacomgain (the cousin of his father Findlaech), his claim was further strengthened under the older alternating order of succession. If tales of the three witches are true, they may have represented the aspirations and influence of Gruoch.