I'm sorry but he's not going to be wounded by 'shrapnel' either. Only the British used this type of ammunition, although the term was later used for the fragments of exploding shell. It was named after the inventor of the 'spherical case shot', as it was called - a Lt. Shrapnel. So he was hit by a piece of shell. And was this Leipzig still? If so it's a bloody long ride to Northern Spain/Southern France where Wellington was at the time.

Have you considered making him an aide-de-camp? Often young Captains (usually well-connected ones) would act as messengers to Generals, called an aide-de-camp, and may be sent to find out what was happening on other parts of the battlefield. Not really scouting as such, which would usually be a small unit of light cavalry. But he could discover some hidden movement of the enemy. The other two scouts could be what remained of a scouting party of Light Dragoons or Hussars (similar toops, different uniforms) and look to him as an officer to lead them.

One prominent member of the Edinburgh Light Dragoons was Sir Walter Scott, although he wasn't 'Sir' until 1820.