How old was Mary, Queen of Scots when she acceded to the Scottish throne?

Mary, Queen of Scots (8 December 1542 – 8 February 1587), also known as Mary Stuart or Mary I of Scotland, reigned over Scotland from 14 December 1542 to 24 July 1567.

Mary was the only surviving legitimate child of James V of Scotland, was six days old when her father died and she acceded to the throne. She spent most of her childhood in France while Scotland was ruled by regents, and in 1558. Mary married the Dauphin of France, Francis. He ascended the French throne as King Francis II in 1559, and Mary briefly became queen consort of France, until his death in December 1560.

Mary had claimed that Queen Elizabeth I of England's throne as her own and was considered the legitimate sovereign of England by many English Catholics, including participants in a rebellion known as the Rising of the North. Perceiving her as a threat, Elizabeth had her confined in various castles and manor houses in the interior of England. After eighteen and a half years in custody, Mary was found guilty of plotting to assassinate Elizabeth in 1586 and was beheaded the following year.