Born in Haddington in 1198, Alexander was coronated on the 5th of December 1214, the day after his father William I died. The speed of the coronation was a reflection of the claim of Donald Ban MacWilliam, in an age when primogeniture was still forcefully challenged. Fortunately for Alexander, this latest MacWilliam threat to the Canmore House was shortlived; Donald Ban died in 1215.
Around this same time disaffected barons in England were pressing King John for concessions that ultimately led to the development of the Magna Carta. Alexander took advantage of this unrest and invaded northern England. As King John moved against his northern barons they turned to the Scots King for help, giving Alexander fealty and homage for their lands. Many of the barons of England asked the heir to the French throne to take the English crown. Thus as the dauphin Louis, son of Phillip II of France, arrived in Kent, Alexander took his army to Dover to meet him. King John, though not wishing to meet this army, marched north and cut the Scots lines of communication. Alexander was forced to return. The subsequent death of King John in 1217, however saw England rally round its new king Henry III and Alexander unluckily lost his opportunity, giving homage to Henry III for his English lands. He married Henry's sister Joan in 1221.
Alexander tried to consolidate his power over the remoter parts of Scotland with campaigns in Argyll and Caithness in 1221-22. As King John had burned down Berwick, Roxburgh and Haddington in raids in 1216, new burghs were also created. In 1222, Alexander was to grant Dumbarton the status of a royal burgh. The burgh was extended with the lands of Murroch in 1224, and in 1226 Alexander gave it the right to have an annual fair for eight days starting on the Feast of St. John the Baptist. The burghers of Dumbarton, considering their Royal status above that of Glasgow's Bishop Burgh, forced the Glasgow traders to pay a 'can' or tax to them on trade with the Lennox. Matters came to a head and Alexander stepped in and declared that the 'bishop's men' were to be can-free in trade with Argyll and the Lennox in 1242.
There is a reference to a grant of King Alexander in 1225 that confirms the birthplace of St. Patrick. As we have seen this birthplace is known by two names; Bannavem Taberniae and Nempthor. The word Nempthor comes from the latin nemetos meaning sacred or noble. W.J. Watson's The Celtic Placenames of Scotland states "The Ravenna Geographer mentions Medio-nemeton, 'mid-shrine' which may have been on the line of the wall between Forth and Clyde". Of course, this backs the claim of Old Kilpatrick as St. Patrick's birthplace.
W. J. Watson, while not definitely asserting Old Kilpatrick's claim, does claim that the region of the Lennox held a town of Nempthor. He uses King Alexander's grant as evidence thus: "Fiacc's hymn to Patrick, composed about 800, begins with the statement 'Patrick was born at Nemthur,' and a gloss that adds that this is the name of a city in North Britain (i mBretnaib tuaiscirt) namely 'Ail Cluade,' that is Dumbarton; another spelling is Nempthor. This original Irish form is considered to stand for an earlier Nemetoduron, 'stronghold of the Nemet'. Now whether Nemthor was really an old name for Dumbarton or not, there was in the neighbourhood, or at least not far away, a place or district called Neved. Maldoven (i.e. Maoldomhnaich), earl of Lennox, granted to his brother Amelec the lands of Neved, Glanfrone (Glenfruin) and other places, and the grant was confirmed by King Alexander in1225." He goes on to explain that that Rosneath, Ros-neimhidh, promontory of the Nemet still carries the name and that a 'Nemeton' existed in the territory of the Damnonians.
In 1230, Alexander put down the latest MacWilliam uprising, culminating in the brutal execution of an infant girl at Forfar market cross - ensuring the end of that family branch. In 1235, the troublesome region of Galloway was subdued by subdividing the Earldom and marrying the Earl's daughters to barons dependent to the crown.
The Peace of York in 1237 settled the Anglo-Scottish border but when Queen Joan died the following year, relations with England once again became tense. Alexander remarried, this time with Marie de Coucy, a daughter of a French noble. She bore him a son, also called Alexander, in 1241.
By this time, only the Lordship of the Isles remained out of Scottish influence. Alexander offered to buy the isles from the Norwegian king Haakon IV but was refused. Thus it was that Alexander organised a naval expedition to resolve the issue. Harboured at the island of Kerrera in Oban bay before mounting the attack, Alexander died suddenly. The ownership of the isles would have to be resolved by his son, the new king Alexander III.