He was not without his troubles, however, for shortly after his succession the Cid quarrelled with one of his nobles.

Next the Moorish kings became disunited and Alfonso's former host summoned him to his aid.

Not only did Alfonso assist this king of Toledo, but invited him into his camp, where he forced him to release him from the promise made on leaving his city.

Not daring to refuse while in the power of the Christians, the Moorish king reluctantly consented, and was surprised and delighted to hear Alfonso immediately renew the oath, for, while not willing to be friends with the Moors under compulsion, he had no objection to enter into an alliance with them of his own free will.
Not long after this the king of Navarre sent forth his champion to challenge one of Alfonso's, the stake this time being three castles which the Cid won.

But the Moors, taking advantage of the Cid's illness which followed this battle, rose up against Alfonso, who was compelled to wage war against them.