White was promoted to major on 10 January 1837 and to lieutenant-colonel (in the 3rd Light Dragoons) on 13 December 1839. White was given command of the cavalry attached to Sir George Pollock's army during the 1842 invasion of Afghanistan. White's troops helped to force the Khyber Pass, take the heights of Jagdalak, defeat an Afghan force at Tezin and capture Haft Kotal. His men were also part of the British garrison at Kabul. Despite the eventual British loss and withdrawal White was recommended for appointment as a Companion of the Order of the Bath, which was granted in 1843, for his services in the war and also received a medal.