The rockets these troops employ are iron tubes filled with gunpowder propellant; when fired in large volleys, the noise alone is unnerving and has a negative effect on enemy morale. Each rocket is laid in an angled launcher, and it is the job of the artilleryman to correctly judge the angle of launch so that the rockets drop in the middle of the enemy. He also needs to take into account wind, as the long tails of the rockets make them inaccurate. The fixed nature of this artillery means the crewmen are incredibly vulnerable to attack, especially from fast moving cavalry.
Historically, it was the Indian war rockets used by Tippu Sultan of Mysore that introduced Europeans to rocket bombardment. The British copied these weapons as the Congreve rocket system, and used them aboard ships as well as on land. A rocket troop was present at the final defeat of Napoleon at Waterloo in 1815, although accounts of their effectiveness vary. Congreve’s system even included illumination rounds to light up the battlefield!