The 4th Division was originally formed in 1809 by Arthur Wellesley, 1st Duke of Wellington, as part of the Anglo-Portuguese Army, for service in the Peninsular War. It fought in the Battle of Talavera and the Battle of Salamanca, Battle of Badajoz and the Battle of Roncesvalles, Battle of Vitoria, Battle of the Pyrenees, Battle of Orthez, Battle of Toulouse.