He was present at the battles of Grossbergen, Dennewitz and Leipzig in October 1813. In his later narrative of the war Vane noted the gallantry displayed by Harris and his "efficient assistance". After the Battle of Leipzig he was presented with a fine sword by merchant and adventurer Edward Solly inscribed with the legend "From Edward Solly To Thomas Noel Harris, In Commemoration Of Their Fellowship At The Memorable Battle Of Leipzig Of The 18th And 19th Of October 1813." In 2015, the sword was sold for £43,750 at a Bonham's auction.