In 1170, Sancho was knighted by his father, King Afonso I, and from that time he became his second in command, both administratively and military. At this time, the independence of Portugal (declared in 1139) was not firmly established. The kings of León and Castile were trying to annex the country and the Catholic church was late in giving its blessing and approval. Due to this Afonso I had to search for allies within the Iberian Peninsula. Portugal made an alliance with the kingdom of Aragon and together they fought Castile and León. To secure the agreement, Prince Sancho of Portugal married, in 1174, princess Dulce Berenguer, younger sister of king Alfonso II of Aragon. Aragon was thus the first Iberian kingdom to recognize the independence of Portugal.
With the death of Afonso I in 1185, Sancho I became the second king of Portugal. Coimbra was the centre of his kingdom; Sancho terminated the exhausting and generally pointless wars against his neighbours for control of the Galician borderlands. Instead, he turned all his attentions to the South, against the Moorish communities that still thrived. With Crusader help he took Silves in 1191. Silves was an important city of the South, an administrative and commercial town with population around 20,000 people. Sancho ordered the fortification of the city and built a castle that is today an important monument of Portuguese heritage. However, military attention soon had to be turned again to the North, where León and Castile threatened again the Portuguese borders. Silves was again lost to the Moors.
Sancho I dedicated much of his reign to political and administrative organization of the new kingdom. He accumulated a national treasure, supported new industries and the middle class of merchants. Moreover, he created several new towns and villages and took great care in populating remote areas in the northern Christian regions of Portugal, notably with Flemings and Burgundians – hence the nickname the Populator. The king was also known for his love of knowledge and literature. Sancho I wrote several books of poems and used the royal treasure to send Portuguese boys to study in European Universities.
Sancho's descendants
Sancho married Dulce Berenguer, daughter of Raymond Berengar IV, Count of Barcelona, and Petronilla, Queen of Aragon.
