a horse led, called le cheval de deuil, covered in black velvet

CHAPERON, CHAPOURN or CHAPERONNE from the old French word for hood, which by metonymy hath given name to the little shields containing deaths-heads, crests or other devices, placed on the foreheads of the horses drawing hearses at pompous funerals. They are called chaperons or shafferoons because these devices were fastened to the chaperones or hoods, formerly worn over the heads of those horses with their other coverings of estate.

CHAPEROON or CHAPERON, by corruption termed shafferoon, [French, chaufries de cheval de deuil.]

Encyclopaedia heraldica or complete dictionary of heraldry, Volume 1

By William Berry