On reaching India in July 1839, Nicholson was ordered to join the 41st Native Infantry at Benares on temporary attachment. After spending four months being drilled on the realities of military life, he was transferred in December, as a regular Ensign, to the 27th Native Infantry based at Ferozepore. Nicholson's arrival in India had been too late to partake in the initial invasion of Afghanistan as part of the First Anglo-Afghan War. However, in November 1840, the 27th Native Infantry was ordered up to relieve one of the infantry units already in Afghanistan as part of the British occupying force and marched through the Khyber Pass and into Afghanistan in January 1841.