Napoleon had abdicated.
After the Battle of the Nive, Arthur Wellesley, Duke of Wellington mounted a surprise amphibious operation which crossed the Adour River estuary and isolated the French city of Bayonne. Wellington pressed east after Marshal Nicolas Soult's French army, leaving the fortress to be invested on February 27 by Hope's corps.
Hope's 19,550-man force included Kenneth Howard's 1st (6,800) and Andrew Hay's 5th (2,750) British Divisions, Lord Aylmer's Independent British Brigade (1,900), Thomas Bradford (1,600) and Archibald Campbell's (2,500) Portuguese Brigades, and Carlos de España's Spanish Division (4,000). Hope's corps was joined by 10,000 Spanish troops in the divisions of Marcilla, Espeleta and Pablo Morillo, but these soldiers were sent away to join Wellington's army in time to fight at the Battle of Toulouse on April 10.
Before retreating, Soult reinforced the garrison with the division of Abbé, raising its strength to 14,000 men. The regular infantry included the 5th and 27th Light, and the 64th, 66th, 82nd, 94th, 95th, 119th and 130th Line Regiments.
Thouvenot received unofficial news of Napoleon's abdication on April 12. Even though this meant that the war was virtually over, the French governor decided to attack "in a fit of spite and frustration." At 3:00 am on the morning of April 14 he attacked the British siege lines with 6,000 men. The fight that followed was vicious but the French sortie was defeated with heavy losses on both sides. "Sir John Hope was wounded and captured after galloping into a melee." The brunt of the battle was borne by the Anglo-German units, including the 1/1st, 3/1st, 1st Battalion Coldstream and 1/3rd Foot Guards; the 3/1st, 1/9th, 1/38th, 2/47th and 5/60th Foot; the 1st and 2nd King's German Legion (KGL) Light battalions, and 1st, 2nd, and 5th KGL Line battalions.
Total losses in the siege, including the battle on April 14, were 1,600 French killed and wounded, plus 400 captured. The Allies lost a total of 1,700 killed and wounded, and 300 captured