The British sent an envoy to Kabul to form an alliance with Afghanistan's emir, Dost Muhammad against Russia.

[1] This led the Governor General of India, Lord Auckland to conclude that Dost Muhammad was anti-British.

This led to Persian troops, along with their Russian allies, attacking the city of Herat in western Afghanistan in an attempt to annex it.

He was the former ruler of Afghanistan and had formed a strategic alliances with Britain during the Napoleonic Wars against Russia and France, but had been deposed and was living in exile in Lahore.

[citation needed] The second Bengal division which was originally supposed to take part in the invasion was now relegated as a reserve force and would remain in India.

[3] Following the agreement between Ranjit Singh and British viceroy Lord Auckland to restore Shah Shoja to the Afghan throne in Kabul, the British army marched towards Afghanistan from the south whereas Ranjit Singh’s army marched through the Khyber Pass, which concluded with the participation in the victory parade in Kabul.

[1] The army's next objective was the fortress city of Ghazni as it commanded the trade routes and roads leading into Kabul.

The severe shortages of supplies along with the lack of draft horses had led to heavy siege equipment being left in Kandahar.

Lacking siege equipment meant that the only way for the British to capture the city was through a frontal attack which would result in heavy casualties.

Thompson spied on the gate and observed an Afghan courier entering the city which confirmed what the prisoners had said.

On July 22, 1839, thousands of Ghilji tribesmen attacked Shuja Shah Durrani's contingent but were repelled.

[2] The rest of the three British regiments formed the main attacking column commanded by Brigadier Sale.

The signal was given to attack and the four regiments led by Lieutenant Colonel Dennie rushed through the shattered gate.

When the Afghan ruler, Dost Muhammad, heard about the fall of Ghazni, he asked for terms of surrender but the British offer was exile in India, which was unacceptable to him.

The Indian Engineers won many awards, with Capt A.C. Peat of the Bombay Sappers winning a Brevet-majority and a C.B.

However, two officers, Lt H.M. Durand and Macleod, who had played critical roles in the assault, were not recognised by the government of India.