I found in Martinien, under 'Aides de camp', p 54:

"De Fitz-James, capt. B. 15 sept, combat de Goerde, pres de Lunebourg."

also located in the same work, under 'Artillerie a cheval, 1er Regiment' p 648:

"Rivocet(1),lieut., B. 16 sept. 1813, a Goerde, pres Hambourg (mort). (1) Godard de Revocet."

I found NO other artillery officer casualties, in either of the two (2) Martinien tomes, for Gohrde. Presumably a company of the 1er regiment de artillerie a cheval was present at Gohrde. This would account for six (6) guns - perhaps there were two (2) pieces of regimental artillerie (3e ligne?) also present. French sources state 6 guns present, but other sources state 8 guns captured.