The perceived offence of an Afghan general's refusal to allow a British envoy entrance to the country was used as an excuse to attack the fortress of Ali Masjid, as the opening battle in the war.

[1] Despite numerous setbacks, including half the troops getting lost or delayed and missing the battle entirely, the British were lucky that the Afghans abandoned their position overnight.

[4] Imagine Helvellyn and Skiddaw, carded into the utmost possible ruggedness and steepness, planted facing each other, with just a quarter of a mile between, and drop into the interval a hill like the great pyramid, but steeper and twice as high, with the battlements of a fort on its flattened top; that is the first view of Ali Masjid.

[page needed] Following the 1837 Battle of Jamrud, Dost Muhammad Khan had built the fortress of Ali Masjid to assert his sovereignty over the Khyber region.

[7] On 21 September 1878, two months before the battle, British envoy General Neville Chamberlain had tried to enter Kabul, but had been ordered to withdraw by Faiz Muhammad, the commander of Ali Masjid.

[2][page needed] At sunset on 20 November 1878 an estimated 1,700 men of the Second Brigade of the Peshawar Valley Field Force began their flank march to assist Browne in his attack on the Ali Masjid fort which guarded the Khyber pass.

[2][page needed] The darkness created confusion and led to men and animals wandering off, it was 10 pm before the troops all reached Lahore settlement, which was only 5.5 km away from Ali Masjid.

[4][9] As the British rushed to bring their own heavy guns up to the ridge, Brigadier-General MacPherson's First Brigade opened fire from the right flank of the fortress.

[2][page needed] The bodies of the dead British troops were buried in a small cemetery which remains today as a reminder of the battle,[13] while the officers were carried back to Peshawar for burial.

[14][page needed] The British victory meant that the northern approach to Kabul was left virtually undefended by Afghan troops.

[17] After the battle, Sher Ali still refused to ask the Russians for military assistance, despite their insistence that he should seek terms of surrender from the British.