The first two troops of Horse Artillery were raised in January 1793 at Goodwood, West Sussex, by the Master-General of the Ordnance, the 3rd Duke of Richmond, to provide fire support for the cavalry. They were joined by two more troops in November 1793. Each troop had six 6-pounder guns. All RHA personnel were mounted. Included in the establishment were 45 drivers and 187 horses, making it the first self-contained fighting unit of artillery.
The regiment wore light cavalry uniforms of blue with gold lace and red facings. Their overalls were grey with a red stripe and on their heads they wore the distinctive "Tarleton" helmets. If needed, they carried 1796 light-cavalry sabres. (source - wikipedia)
Illustration by David Higham