king of Dal Riada (839-858)
king of Pictavia (847-858)
His name wasn't really Kenneth, but rather the Goidelic equivalent which is variously rendered as Kinet, Ciniod or Cinaeda or Cinaedius even in its Latin version, but he is universally known these days under his Anglicised name of Kenneth. He is a man of great symbolic significance in the history of Scotland because he is frequently allocated a role as the founder of the kingdom of Scotland.
In tradition
The traditional tale is that his father was Alpin mac Eochaid, king of Dal Riada (and leader of the Dal Riadan resistance the Pictishrule of Eoganan son of Oengus) who married the daughter of the second Oengus son of Fergus king of the Picts. Kenneth mac Alpin was therefore heir to Dal Riada by virtue of his father and heir to Pictavia as Pictish succession was matrilinear1.
However there is no mention of any 'Alpin' as king of Dal Riada in any of the Irish Annals for the relevant period neither is there any remotely contemporary record of his marriage to a Pictish heiress. As is often the case, with kings from Britain's Dark Ages, genealogies are more a matter of politics than fact, constructed by later propogandists to bolster the claims of the dynasty as the 'natural' rulers of the nation.
The tale is further embelished by the event known as Mac Alpin's treason which recounts how Kenneth invited the leading Pictish nobles to a banquet only to treacherously massacre them, uisng some dubiously complicated methods. A tale that is almost certainly without any historical foundation although it may record a certain metaphorical truth relating to mac Alpin's treatment of Pictish opposition.
In history
The reality is that his origins are obscure and that he was most likely a pure adventurer who allied himself with some Norse Vikings and seized power in the Hebrides in 836, taking advantage of the general disruption being caused by Viking incursions throughout the north.
Eoganan son of Oengus, the contemporary ruler of Pictavia, whose rule extended over Dal Riada, suffered a disastrous defeat against the Vikings in 839. Eoganan together with huge swathes of his supporters was killed, creating a power vacuum which Kenneth mac Alpin was only to willing to fill. He was able to usurp the throne of Dal Riada in 840, and the then sought to extend his rule eastwards over the Picts but diidn't succeed in a similar usurpation of the Pictish throne until 847 when he defeated Durst at Forteviot.
How he actually gained power over the two kingdoms isn't exactly known. The tale of Mac Alpin's treason provides a neat, if unlikely explanation for how this was achieved. Some have even suggested that the Picts willingly accepted his rule as the price of protection against the Viking threat.
But we have evidence that Aethelred II king of Northumbria sent military assistance to the Picts, and the Pictish Chronicle which lists the Kings of Pictavia continues to show a series of successors to the departed Eoganan before finally noting the name of Kinadius son of Alpin. It is therefore very unlikely that it was peaceful. (But then these things never are.)
Apart from moving his capital eastwards to Forteviot and dividing up the relics of Columba previously located at Iona2, nothing much is known of what Kenneth mac Alpin did with the power he had won. His three daughters were married off in a series of strategic alliances with neighbouring rulers; one to Rhun map Artgal of Strathclyde, one to Aedh Finnlaith High King of Ireland and one to Olaf the White the Viking King of Dublin.
He died at Forteviot in 858 and was buried on Iona. His successor was his brother Donald.
In conclusion
Despite his popular reputation he was not the first king to rule over both the Scots3 and Picts nor the first king of Scotland4. Both Dal Riada and Pictavia had spent the last century or more squabbling over the dominance of the extreme north of Britain, with a succession of kings claiming dominion over both; Kenneth mac Alpin was simply the latest and the one that managed to make it stick.
Even then his rule over Pictavia was limited to the south, to Fortrenn and the Mearns, as Caithness and the north was in Viking hands. Claims that Kenneth extended the boundaries of the kingdom to the Tweed are entirely spurious, although he no doubt raided Lothian he did not conquer it and it remained in English hands for a century or so after his death5.
What he did do however was establish a dynasty that surpressed any notions of Pictish independence. He successfully transmitted his power to his brother Donald and both of his sons, Constantine and Aedh would become kings of Alba in their turn. Indeed the House of Alpin would provide the now united kingdoms of Dal Riada and Pictavia with its rulers for almost two centuries, right down to the time of Malcolm II.
NOTES
1 In any event, Pictish matrilinear succession did not mean that succession followed through one specific female line, but rather that it determined the candiates for selection when a vacancy arose
2 Presumably to avoid Viking depredations; half went to Ireland and half were retained by Kenneth and moved to Dunkeld.
3 That would be the first Oengus son of Fergus had already managed it a century or more before.
4 Malcolm II is a much better candidate.
5 Lothian was still formally part of Northumbria until 867, thereafter under the control of the Lordship of Bamburgh.
SOURCES
A Biographical Dictionary of Dark Age Britain by Ann Williams, Alfred P. Smyth and D. P. Kirby (Seaby 1991)
The Scottish Radiance website at http://claymore.wisemagic.com/scotradiance/scothistory/scothistory01.htm as well as http://members.tripod.com/~Halfmoon/pict4 and www.bartleby.com/65/ke/Kenneth1.html