The weather was on the side of the Anglo/Spanish troops. During the first few days the rain was so bad, the French trenches filled with water and whole areas became masses of deep mud. When the weather cleared on the night of December 28th, ten guns were dragged into place and the following morning they opened up on the eastern wall, making a large breach. The breach left Tarifa open to attack but Captain Smith of the Engineers noticed that the street level was 6 metres lower than the breach in the wall. This meant that the attacking French would have to jump down onto the street. Smith continued to cover the street with metal window frames with the sharp metal pointing upwards.

On December 30th the French sent in a summons to surrender. This was rejected and the guns continued to pound the defences. By December 30th the breach was 20 metres wide. The French began to advance the following morning but the rain came again and washed the French camp down the hillside. The wreckage crashed into the defences, making a new breach in the walls. Repairs were made during the night but the following morning the French were seen opposite the walls, advancing through the rain. Due to the rain they lost their way and ended up near the portcullis. As a result they suffered side fire from inside the walls. The commanding officer was killed and the troops scattered. In the end they had to retreat. They left behind 207 men including 47 dead. This destroyed the moral of the French troops who were already suffering of lack of food. The rain had filled the trenches and washed away the guns. The ammunition was ruined and the troops were in rags. This was their only attack and a few days later they withdrew. The campaign was a total disaster and cost the French over 500 troops, most of their artillery and all their stores and ammunition.

The breach was repaired and on it was placed the following inscription:

HANC PARTEM MURI A GALLIS OBSIDENTIBUS DIRUTAM BRITANNI DEFENSORES CONSTRUXERUNT, 1812.