As some of the Moors had helped the invaders, the Cid next proceeded to punish them, and gave up the siege of Saragossa only when the inhabitants made terms with him.

This campaign won for the Cid the title of "Campeador" (Champion), which he well deserved, as he was always ready to do battle for his king.
While Don Sancho and his invaluable ally were thus engaged, Don Garcia, King of Galicia, who was also anxious to increase his kingdom, deprived his sister Dona Urraca of her city of Zamora.

In her distress the infanta came to Don Sancho and made her lament, thereby affording him the long-sought pretext to wage war against his brother, and rob him of his kingdom.
This war, in which the Cid reluctantly joined, threatened at one time to have serious consequences for Sancho.

He even once found himself a prisoner of Garcia's army, shortly after Garcia had been captured by his.

The Cid, occupied in another part of the field, no sooner heard of this occurrence than he hastened to the Galician nobles to offer an exchange of prisoners; but, as they rejected his offer with contempt, he soon left them in anger.
"'Hie thee hence, Rodrigo Diaz, An thou love thy liberty; Lest, with this thy king, we take thee Into dire captivity.'" _Ancient Spanish Ballads_ (Lockhart's tr.).
The wrath which the Cid Campeador experienced at this discourteous treatment so increased his usual strength that he soon put the enemy to flight, recovered possession of his king, and not only made Don Garcia a prisoner, but also secured Don Alfonso who had joined in the revolt.