I always try to make a pair of books for a period I'm interested in: one comprehensive history of the major events and people of the period, and one personal story. (For instance, the late 1800s/early 1900s incl WW1, I have "Dreadnought" by RKM and "Storm of Steel" by Junger).
For the time before and during the first Afghan War, I can highly recommend:
1) Maybe the best-researched, most vivid, and most comprehensive overall telling of the before, during and after of the First Afghan War: the book Return of a King, by Dalrymple. It incorporates a lot of surprisingly-recently-translated documents from libraries in modern-day Pakistan, which became more interesting to historians post-2001.
2) A personal story, that of the American Josiah Harlan, the book Josiah The Great. Like Gardener was a wanderer and soldier of fortune, but who unlike Gardener was the inspiration for Kipling's short story written after the publication of the first part of his memoirs (and later movie with M. Caine and S. Connery). His story has a lot of detail, because he was a weird duck who kept to himself, brought a personal library with him, and took extensive notes for his memoirs. In fact he's a high-quality primary source in book (1). As a result, there's a lot of detail. You can really feel the personal danger Harlan was in, and just how often he bluffed his way through situations that could easily have killed him.
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