When Arthur Conan Doyle introduced his famous narrator of the Sherlock Holmes tales in 'A Study In Scarlet' (1887) he also introduced into Doctor John H. Watson's background a history serving in the Afghan theatre of war from 1878 to 1880, the tale of his wounding at the Battle of Maiwand, and his return home on the troopship Orontes, before he met up with Holmes in a chemical lab in London. Here the burgeoning detective uttered one of the most famous introductory lines in literature, "How are you? You have been in Afghanistan, I perceive"
How did Sherlock Holmes know Dr. Watson had been in Afghanistan? Later on in A Study in Scarlet, Holmes says:
"I knew you came from Afghanistan. From long habit the train of thoughts ran so swiftly through my mind that I arrived at the conclusion without being conscious of intermediate steps. There were such steps, however. The train of reasoning ran: "Here is a gentleman of a medical type, but with the air of a military man. Clearly an army doctor then. He has just come from the tropics, for his face is dark, and that is not the natural tint of his skin, for his wrists are fair. He has undergone hardships and sickness, as his haggard face says clearly. His left arm has been injured. He holds it in a stiff and unnatural manner. Where in the tropics could an English army doctor have seen much hardship and got his arm wounded? Clearly in Afghanistan." The whole train of thought did not occupy a second. I then remarked that you came from Afghanistan, and you were astonished."
We'll forgive him the fact that Afghanistan is not actually tropical, and the Zulu War could have been, perhaps, a stronger contender for Dr. Watson's recent adventures!