One might be inclined to speculate on the curious incident of Watson’s wound because it certainly did more than nothing! In the second paragraph of the very first story Watson writes the following: “I was removed from my brigade and attached to the Berkshires, with whom I served at the fatal battle of Maiwand. There I was struck on the shoulder by a Jezail bullet, which shattered the bone and grazed the subclavian artery.” Sherlock Holmes, when explaining his reasons for knowing that Watson had been in Afghanistan, says, in part, the following: “His left arm has been injured. He holds it in a stiff and unnatural manner.” It is indeed curious that, towards the end of the story, Watson is able to carry a dog up the stairs with his arm is such a state.
By the time of the next story, ‘The Sign of Four,’ the wound has migrated for Watson writes: “I . . . sat nursing my wounded leg. I had had a Jezail bullet through it some time before, and, though it did not prevent me from walking, it ached wearily at every change of the weather.” By the time of ‘The Adventure of the Noble Bachelor,’ the wound has become positively lost for Watson writes: “I had remained indoors all day, for the weather had taken a sudden turn to rain, with high autumnal winds, and the jezail bullet which I had brought back in one of my limbs as a relic of my Afghan campaign, throbbed with dull persistency.” Once more, in ‘The Cardboard Box’ Holmes says to Watson, “Your hand stole towards your old wound . . . .” The wound next disappears completely for it is never mentioned again in any of the stories.
Although Watson is wounded a second time in ‘The Adventure of the Three Garridebs,’ and the wound appears to be in the thigh — definitely.