The Marinid ruler Abu al-Hasan Ali ibn Othman allied with his Granadan counterpart, Muhammed IV, to mount a siege of the fortified town between February–June 1333.

His army's overland march from Jerez de la Frontera had been held up by squabbles with his nobles, whom he had to persuade to continue on after the news of Gibraltar's fall arrived on 20 June.

[1] The Castilians left their encampment by the Guadalete river near Jerez and marched first to Alcalá de los Gazules, taking the direct but mountainous route to Gibraltar.

Alfonso stuck to the high ground of the Sierra Carbonera from which the Moors sought to lure him into an ambush as his army descended the slope towards Gibraltar.

[3] However, Alfonso's field commanders – Rui Lopez and Fernan Yañez de Meira – failed to control their troops or coordinate their landings.

He reluctantly agreed to his nobles' insistence that they had to withdraw to Castilian territory, abandoning the men left on the Rock, who were to "take their stand on whatever God might wish to give them.

Accounts differ as to what happened; some say that Alfonso persuaded his nobles that it would be dishonorable to abandon the trapped men, while others say that the winds changed at the last minute and permitted the resupply vessels to enter the bay after all.

[6] The Castilians sought to overwhelm the Moors by rushing them en masse, using every small boat at their disposal to carry soldiers, crossbowmen and even cavalry with their horses.

His move failed, as the Moors had built a heavy roof over the dockyard to protect ships there from bombardment and had emplaced massive wooden booms across the entrance to prevent enemies from gaining access.

The naval attack was beaten back with heavy loss of life, but Jofre did succeed in establishing an effective blockade of Gibraltar's sea routes.

[4] The Castilians dug in around Gibraltar to lay siege from the south, from the high ground of the Upper Rock and from the isthmus to the north, where Alfonso remained with his main force.

[8] This successfully deterred Muhammed IV from attacking, but cut the Castilians off from their supply of firewood in the hills of the Sierra Carbonera; henceforth, they had to eat their food raw.

The agreement which was eventually signed on 24 August 1333 was based on a Moorish proposal for a four-year truce and an annual tribute of 10,000 doubloons to be paid to Castile.

[4] The Castilian king accepted and sealed the agreement in person with Muhammed IV at a lavish dinner in which he exchanged gifts with his Moorish counterpart.