What Is The Connection Between Merlin And Stonehenge?

Geoffrey of Monmouth, in his book History of the Kings of Britain, which was written in Latin in the 12th century and freely mixes history and legend, first wrote about the connection between the magician Merlin, and Stonehenge. He said that the British king Aurelius Ambrosius, had commanded Merlin to build a memorial to some British noblemen who had been murdered by the Saxons. Merlin obtained the stones from Ireland, from the mountain Killaraus, where they were said to have been brought originally by giants from Africa who prized them for their healing properties, and who lived in Ireland for a while.
According to the legend, a force of 15,000 knights had to accompany Merlin into Ireland and subdue an Irish army led by the Irish king Gillomanius before the stones could be taken. Monmouth claimed that both Aurelius Ambrosius and his brother and successor Uther Pendragon were buried at Stonehenge.