Grelet was nominated on 18 May 1807, still a sergent-major:
https://books.google.de/books?id=KF02WJRVvQYC&pg=PA244
And it sems he was killed at Albuera:
https://books.google.de/books?id=fRgqxOar7MUC&pg=P368&dq=grelet