The 19th century was a period of diplomatic competition between the British and Russian empires for spheres of influence in South Asia known as the "Great Game" to the British and the "Tournament of Shadows" to the Russians. With the exception of Emperor Paul who ordered an invasion of India in 1800 (which was cancelled after his assassination in 1801), no Russian tsar ever seriously considered invading India, but for most of the 19th century, Russia was viewed as "the enemy" in Britain; and any Russian advance into Central Asia, into what is now Kazakhstan, Turkmenistan, Kyrgyzstan, Uzbekistan and Tajikistan, was always assumed (in London) to be directed towards the conquest of India, as the American historian David Fromkin observed, "no matter how far-fetched" such an interpretation might be. In 1837, Lord Palmerston and John Hobhouse, fearing the instability of Afghanistan, the Sindh, and the increasing power of the Sikh kingdom to the northwest, raised the spectre of a possible Russian invasion of British India through Afghanistan. The idea that Russia was a threat to the East India Company is one version of events. Scholars now favour a different interpretation that the fear of the East India Company was in fact the decision of Dost Mohammed Khan and the Qajar Ruler of Iran to form an alliance and extinguish Sikh rule in Punjab. The British feared that an invading Islamic army would lead to an uprising in India by the people and princely states therefore it was decided to replace Dost Mohammed Khan with a more pliant ruler.

On 1 October 1838 Lord Auckland issued the Simla Declaration attacking Dost Mohammed Khan for making "an unprovoked attack" on the empire of "our ancient ally, Maharaja Ranjeet Singh", going on to declare that Shuja Shah was "popular throughout Afghanistan" and would enter his former realm "surrounded by his own troops and be supported against foreign interference and factious opposition by the British Army". Lord Auckland declared that the "Grand Army of the Indus" would now start the march on Kabul to depose Dost Mohammed and put Shuja Shah back on the Afghan throne, ostensibly because the latter was the rightful Emir, but in reality to place Afghanistan into the British sphere of influence. Speaking in the House of Lords, the Duke of Wellington condemned the invasion, saying that the real difficulties would only begin after the invasion's success, predicting that the Anglo-Indian forces would rout the Afghan tribal levy, only to find themselves struggling to hold on, as the Hindu Kush mountains and Afghanistan had no modern roads, and calling the entire operation "stupid" since Afghanistan was a land of "rocks, sands, deserts, ice and snow".