Constantine II of Scotland

Causantín mac Áeda, or Constantine II, was born no later than 879 and ruled as King of Alba (modern-day Northern Scotland) from 900 to 943. The kingdom's heartland lay around the River Tay, stretching from the River Forth in the south to the Moray Firth and possibly Caithness in the north. Constantine's grandfather, Kenneth I of Scotland, was the first in the family to be recorded as king, initially ruling over the Picts. During Constantine's reign, the title shifted from "king of the Picts" to "king of Alba," signaling the transformation of Pictland into the Kingdom of Alba.

Constantine's reign was dominated by the incursions and threats from Viking rulers, notably the Uí Ímair dynasty. In the early 10th century, Viking forces plundered Dunkeld and much of Albania. Constantine successfully repelled these attacks, securing his kingdom against further Norse incursions. However, his reign also saw conflicts with the southern Anglo-Saxon rulers. In 934, King Æthelstan of England invaded Scotland with a large force, ravaging parts of southern Alba, though no major battles are recorded.

In 937, Constantine allied with Olaf Guthfrithson, King of Dublin, and Owain ap Dyfnwal, King of Strathclyde, to challenge Æthelstan at the Battle of Brunanburh. This coalition was defeated, marking a significant but not conclusive victory for the English. Following this defeat, Constantine's political and military power waned.

By 943, Constantine abdicated the throne and retired to the Céli Dé monastery of St Andrews, where he lived until his death in 952. His reign, notable for its length and influence, saw the Gaelicisation of Pictland and the solidification of Alba as a distinct kingdom. The use of "Scots" and "Scotland" began during his time, and the early ecclesiastical and administrative structures of what would become medieval Scotland were established.