Donald I (a.k.a. Domnall mac Ailpín) followed his brother Kenneth Macalpin to the throne. Although Kenneth had left sons tradition then did not dictate that they should follow their father to the thrown.
Donald was born in 813. As the King if the Picts and Gaels Donald had hard footsteps to follow; Kenneth had been a mighty power and left quite a larger Kingdom to defend. Donald was described as ‘wanton’ a bit of a playboy prince , slightly carefree. He was also described as being the “son of a foreign wife” implying that his father, Alpin, took a second wife. Some historians have speculated that this may have been to a Viking bride.
His brother’s victories and the growth of the Kindom were consolidated in Donald’s reign. It was his role to suppress any further challenge to the House of Alpin from the Pictish nobility for the Pictish Crown. He also oversaw the introduction of a set of laws known as the Laws of Aedh (or Aed). These included the law of tanistry, under which the successor of a king was elected during his lifetime from members of his family: often a brother or cousin rather than a son. The aim was to ensure that in an age when very few men died old, the succession would pass on to someone old enough and able enough to handle it.
The Chronicle of the Kings of Alba says that Donald I reigned for four years.
Donald was eventually killed in battle in 863. Some say it was at the battle of Scone of Scone on April 13th. The Chronicle of Melrose recorded that he was “assassinated at Scone” but there is no other evidence to suggest foul play.
The Chronicle of the Kings of Alba, a king-list of the Scottish monarchs from Kenneth MacAlpin to Kenneth II completed in c. 1200 states:
“Donald, [Kenneth’s] brother, held the same kingdom for 4 years. In his time, the Gaels established the rights and laws of the kingdom of Áed the son of Eochaid, with their own king at Forteviot. He died in the palace of Cinn Belachior on the Ides of April.”
Belachior is thought to be a church settlement near Scone, at the heart of the Pictish kingdom.
Donald was buried on Iona next to his his brother. He died without leaving any heirs and it was his nephew Constantine who succeeded him to the throne.