Sancho III of Castile

Sancho III (c. 1134 – 31 August 1158), called the Desired (el Deseado), was King of Castile and Toledo for one year, from 1157 to 1158. He was the son of Alfonso VII of León and Castile and his wife Berengaria of Barcelona, and was succeeded by his son Alfonso VIII. His nickname was due to his position as the first child of his parents, born after eight years of childless marriage.

During his reign, the Order of Calatrava was founded. It was also in his reign that the Treaty of Sahagún in May 1158 was decided.

Source: Wikipedia — https://en.wikipedia.org/wiki/Sancho_III_of_Castile