Wellington decided to make his main assault on the south-east side of the town, first taking out Fort Picurina which lay on the eastern bank of the River Rivellas covering this approach. Twelve gun battery positions gave fire support to pound the defensive works and to provide covering fire for the assaulting troops. The Allies invested Badajoz on 16 March and launched their attack on Fort Picurina on 25 March; 500 men of the 3rd and Light Divisions led the assault. The bombardment had made a small breach in the defences, but the ladders were too short to reach the top of the walls. This and the withering French defensive fire caused heavy casualties – 300 killed or wounded.

Eleven days of bombardment and the frantic and dangerous digging of trenches continued until the main attack on the east side of the city on 6 April. The 4th and Light Divisions formed the left flank of the attack, with the 5th Division in the centre, and Picton’s 3rd Division on the right flank. At the same time, two brigades from the 5th Division and the Portuguese made a diversionary attack on the north-west sector of the city. But, as seasoned soldiers know, no plan survives contact. The attacks, led by the aptly named Forlorn Hope – the assault party always oversubscribed by eager volunteers – were thrown back time and time again. Again the ladders were too short. Again the ditches filled up with the dead and dying. In the melee, command and control became impossible. Harry Smith, in the forefront of the Light Division attack, described the chaotic and lurid scenes as they tried to climb the escalades:

When the head of the Light Division arrived at the ditch of the place it was a beautiful moonlight night. Old Alister Cameron was in command of four Companies of the 95th Regiment, extended along the counterscape to attract the enemy’s fire, while the column planted their ladders. He came up to Barnard and said, ‘Now my men are ready; shall I begin?’ ‘No, certainly not,’ says Barnard. The breach and the works were full of the enemy, looking quietly at us, but not fifty yards off and most prepared, although not firing a shot. So soon as our ladders were all ready posted, and the column in the very act to move and rush down the ladders, Barnard called out, ‘Now, Cameron!’ and the first shot from us brought down such a hail of fire as I shall never forget, nor ever saw before or since. It was most murderous. We flew down the ladders and rushed at the breach, but we were broken, and carried no weight with us, although every soldier was a hero. The breach was covered by a breastwork from behind, and ably defended on the top by chevaux-de-frises of sword-blades, sharp as razors, chained to the ground; while the ascent to the top of the breach was covered with planks with sharp nails in them. However, devil a one did I feel at this moment. One of the officers of the forlorn hope, Lieut. Taggart of the 43rd, was hanging on my arm – a mode we adopted to help each other up, for the ascent was most difficult and steep. A Rifleman stood among the sword-blades on the top of one of the chevaux-de-frises. We made a glorious rush to follow, but, alas! in vain. He was knocked over. My old captain, O’Hare, who commanded the storming party, was killed. All were awfully wounded except, I do believe, myself and little Freer of the 43rd. I had been some seconds at the revêtement of the bastion near the breach, and my red-coat pockets were literally filled with chips of stones splintered by musket-balls. Those not knocked down were driven back by this hail of mortality to the ladders. At the foot of them I saw poor Colonel Macleod with his hands on his breast – the man who lent me his horse when wounded at the bridge on the Coa. He said, ‘Oh, Smith, I am mortally wounded. Help me up the ladder.’ I said, ‘Oh no, dear fellow!’ ‘I am,’ he said; ‘be quick!’ I did so, and came back again. Little Freer and I said, ‘Let us throw down the ladders; the fellows shan’t go out.’ Some soldiers behind said, ‘D— your eyes, if you do we will bayonet you!’ and we were literally forced up with the crowd … So soon as we got on the glacis [the brickwork sloping defensive plate], up came a fresh Brigade of the Portuguese of the 4th Division. I never saw any soldiers behave with more pluck. Down into the ditch we all went again, but the more we tried to get up, the more we were destroyed. The 4th Division followed us in marching up to the breach, and they made a most uncommon noise. Both Divisions were fairly beaten back; we never carried either breach.

By midnight not a single British or Portuguese soldier had penetrated the defences, and the ditches overflowed with the dead and dying. Even the ebullient Smith was close to despair. Then to their amazement, they heard Allied bugle calls from within the city. Ironically, having spent weeks on creating breaches in the town walls, the successful assaults were actually made by escalade. Picton’s 3rd Division in the north-east had crossed the River Rivellas and, despite fierce French opposition, managed to scale the walls, but not to gain an entrance. The ladders were too short in many cases and men had to stand on each other’s shoulders to reach the top of the walls. Colonel Ridge of the 5th Foot (later the Northumberland Fusiliers) led the charge which broke the enemy’s resolve but cost him his life. (He was reputed to be the first of Wellington’s men into Badajoz.) In contrast to the repulse of the earlier attacks, the diversionary attack on the north-west sector by the brigades from the 5th and Portuguese Divisions, in spite of initially losing their way, broke in and effectively turned the French defences. Their success galvanized the other attackers to a final desperate and ultimately successful effort, but such was the strength of the defences that the 4th and Light Divisions were still unable to penetrate the walls until first light. Then the breaches were carried and there followed several hours of murderous hand-to-hand fighting. As the Allies broke in, General Phillippon rapidly withdrew his troops to the San Christobal fortress on the north bank of the River Guadiana, and at 7.00am on 7 April 1812 surrendered the city. Then the mayhem began.