At the age of 14, Sancho the Noble or Sancho of Peñalén was proclaimed King of Navarre in the camp by the field where his father was killed at the Battle of Atapuerca. Sancho's mother served as his regent, until she died in 1058. Faithful to her husband's wishes, she continued the support of the monastery he founded at Nájera, where Navarrese monarchs are interred.
With his uncle, King Ramiro of Aragon, he forced al-Muqtadir, king of Zaragoza, into submission and exacted a tribute.
He was in constant conflict with Castile, culminating in the so-called War of the Three Sanchos (1067–1068). Years before, Sancho's father had managed to retain a series of frontier lands, including Bureba and Alta Rioja, which had been claimed by Ferdinand I of Castile. Ferdinand's son, Sancho II the Strong sought to reconquer these lands for his kingdom. Faced with an invasion by his cousin the Castilian Sancho, The Navarrese Sancho asked for aid from his other cousin, Sancho of Aragón. But their forces were defeated by Sancho the Strong and his trusted alférez (supreme commander) El Cid. Sancho lost Bureba, Alta Rioja, and Álava to Sancho of Castile.
He was assassinated in Peñalén, whence his nickname, by a conspiracy headed by his brother Ramón and his sister Ermesinda. During a scheduled hunt, Sancho was forced from a cliff by his siblings. Upon his assassination, Navarre was invaded and ultimately partitioned between Sancho of Aragon and a third cousin, Alfonso VI of León and Castile. Alfonso occupied La Rioja and Sancho was proclaimed king in Pamplona.
|Offspring of Sancho IV of Navarre and Placienda of Normandy (?-1088)|
|Garcia of Navarra (c1069-c1069)|| |
|García of Navarre (?-aft1091)|
|Offspring of Sancho IV of Navarre and Jimena|
|Ramón of Esquiroz (?-?)|| |
|Urraca of Navarre (?-?)|