On 24 August 1154, probably in the city of Toledo, Fernando Yáñez had a charter drawn up. Under the terms of the document, the magnate made over his estate in the village of Oliveira to the nearby cathedral church of Túy. We have no further record of the Galician noble after this date and it is just possible that he made the grant to Túy on his deathbed. The diploma does not amount to a will as such, but it has something of a leavetaking tone to it. As he cast his mind back across his long and highly successful career, Fernando recalled that he had been granted the estate at Oliveira way back in the days of Queen Urraca in whose service he had prospered. He also paid warm tribute to the generosity of the queen's son, Alfonso VII, who by showering him with honours and by protecting him from his enemies had enabled him to thrive.

As the career of Fernando Yáñez so amply illustrates, the relationship between monarch and nobleman in twelfth-century León and Castile, far from being characterised by endemic suspicion or even outright hostility, was based above all upon mutual support and co-operation. The two parties had much to offer one another. For the monarch, lacking a professional army, the military service and contingents of troops provided by his magnates were indispensable if he wished to wage war against his enemies.