General Roberts' tent

General Roberts in his tent, with his 2 Gurkha, 2 Sikh and 2 Pathan orderlies standing watch outside. 4th Punjab Infantry

General Roberts during the invasion of Afghanistan in 1879: his tent actually has furniture in it.  
The Second Afghan War was the result of the overturn of a diplomatic treaty between Russia and India by Lord Lytton who wanted regime change in Afghanistan deposing Sher Ali, the Amir and studiously neutral, friends with both Russia under Tsar Alexander II and Britain under Queen Victoria, then Yacub Khan who drew a pension from both the Russians and the British, for Abdur Rahman, a steadier friend of the British.  Well, it is all much more complex than this; Persia, now Iran was involved, it had started with the First Anglo-Afghan War in 1838, and continued on to the Third Anglo-Afghan War of 1919.  Isn't it interesting how some things never change.  

Soldiers such as the Highlanders and the Liverpool Regiment found the terrain impossible, the summer weather unbearable, the winter weather bitter, the enemy invisible, allies such as the 29th Punjabis, divided in their loyalties – they were probably saved by the 5th Gurkhas and an implacable sense of historical right.

Nineteenth-century Russia was as imperialistic as Britain.  Russia wanted access through the Straights of Constantinople, and so wanted Turkey. Turkey had been allowed independence by Britain whose navy was able to blockade the Dardenelles and thus the Black Sea and all the Russian ports.  If they did that, Russia threatened to cross Afghanistan and take India.  But India was the jewel in the crown of the British Empire: it wasn't going to happen.  The Great Game, it continues.