[Minor edits made 12-18-09]
In my last post, I described how early in the battle of Cowpens, the American Brigadier-General Daniel Morgan ordered forward detachments from the militia line to engage the enemy.
Major Joseph McJunkin of South Carolina recalled that General Morgan rode up to where he was posted and asked, "Boys, who will bring on the battle?" When McJunkin and a number of others volunteered, Morgan told them to, "Go & bring on the action." According to McJunkin, soon "A column" marched towards them, "led by a gayly dressed officer on horseback." This officer, according to Thomas Young, began "calling them in a loud voice 'dam’d Rebels,'" and, "ordered them to disperse." At this point, John Savage, one of the riflemen with McJunkin, "darted a few paces in front, laid his rifle against a sapling," and fired. "[A] blue gas streamed above his head, the sharp crack of a rifle broke the solemn stillness of the occasion and a horse without a rider wheeled from the front of the advancing column." According to Young, "John Savage, in my opinion fired the first gun at the Battle of the Cowpens."
So who was this British officer, the likely first casualty of the battle of Cowpens? There is of course no way to know for certain, but it is possible through deduction to produce some likely candidates.
Presumably, this officer would have been with one of the first British units to approach the Americans. The first British troops on the scene, according to the memoir of British commander Lieutenant-Colonel Banastre Tarleton, was a vanguard of dragoons. However, McJunkin referred to an "officer on horseback," leading "a column." This strongly suggests an officer at the head of a column of infantry (to say he was mounted would otherwise have been redundant).
Next to arrive were several companies of light infantry. The light infantry would also not seem to be a good place to find John Savage's victim. Tarleton's account indicated that the light infantry were deployed on the extreme right of the British line, while Morgan's report indicated that the South Carolinia regiment to which Savage belonged was opposite to the British left.
Therefore, it would seem that Savage's victim was most likely with the 7th Regiment of Foot, which deployed in the vicinity of these skirmishers. The men in the 7th Foot were relatively inexperienced and an officer of that regiment could plausibly have been "gayly dressed," as described by McJunkin, or exhibited the fatal hubris described by Young.
John Moncure's The Cowpens Staff Ride and Battlefield Tour webpage has a transcription of some of the statements made by Samuel Hammond, Thomas Young, Banastre Tarleton, and Daniel Morgan in connection with Cowpens.
James Saye. Memoirs of Major Joseph McJunkin, Revolutionary Patriot.
Will Graves. (2005). What Did Joseph McJunkin Really Saye? Southern Campaigns of the American Revolution, Volume 2, Issue 11. (.pdf file).
Will Graves transcribed the pension application of John Jolly, which includes a supportive statement by Thomas Young. (.pdf file).