In 1833 he entered the Royal Military Academy, Woolwich, having been nominated for a cadetship by Lord Beresford but was withdrawn after a year when it became clear he was unlikely to pass the final examinations.

[2] During his time at Woolwich he earned a reputation for fighting and rebellious behaviour, and on his return home he threatened to join the British Legion, a body of troops leaving for Spain under Sir George de Lacy Evans.

[2] Instead, he was encouraged to pursue a career in India, and with help from his late father's contacts he was commissioned as an ensign in the Bengal Native Infantry on 24 February 1837.

He remained at Madras for a short time as the guest of the retired general Sir John Doveton before continuing on to Calcutta in June.

[11] Chamberlain was reappointed to the command of the Punjab Irregular Frontier Force in 1858 and led it during the Ambela Campaign during which he was again severely wounded again in November 1863.

[7] Advanced to Knight Commander of the Order of the Bath on 11 April 1863,[12] he returned to the United Kingdom and was promoted to major-general for distinguished service on 5 August 1864.

[17] Chamberlain became Commander-in-chief of the Madras Army in February 1876 and, having been promoted to full general on 1 October 1877,[18] was sent on a mission to the Emir of Afghanistan, Sher Ali Khan, whose refusal to allow him, along with Major Louis Cavagnari, to enter the country precipitated the Second Anglo-Afghan War in November 1878.