Some suggested starting points for you: 

1. Royal Artillery Museum Woolwich for Rockets ( I believe they have some on display) and also for leads on the records of the Royal Artillery and the Royal Military Academy Woolwich. It might also be worth contacting Woolwich Public Library who have quite a good local records section.

2 - Article on Sir William Congreve by Col J R.J. Jocelyn, Journal of the Royal Artillery vol xxii, no 2 1905. This may be the source of the information in the Encyclopaedia Britannica that reads : "That same year (1813) the new "Rocket Troop" of the Royal Artillery rendered excellent service at Leipzig. Congreve's rocket was replaced by Hale's, which had no stick."

3. Picture of Battle of Leipzig  2nd Rocket Troop Royal Horse Artillery in action against  Napoleon's army  can be seen at: http://www.warart.com/hist2.html

(This I suppose implies that there must have also been a 1st Rocket Troop!)

4. Anglo-German Family History Society (England) - HOMEPAGE http://feefhs.org/uk/frgagfhs.html

5. Re Leipzig  and the site of the battle
Go to the "Colditz Gateway to Saxony" Home Page at 
http://www.cimttz.tu-chemnitz.de/colditz 
and follow up links to Leipzig. Also leave your query in the Colditz visitor's book, because a lot of people with an interest in the history of Saxony sign in and one of them may be able to help you.



Hope this is some use to you.



Antony Anderson
[log in to unmask]
Colditz Gateway to Saxony
http://www.cimttz.tu-chemnitz.de/colditz
----------
From:   kiz Stonell[SMTP:[log in to unmask]]
Sent:   24 June 1997 19:48
To:     [log in to unmask]
Subject:        John Guy - Battle of Leipzig

I am after as much information about the Battle of Leipzig, the English
Rocket Troop, and their part in it, as possible.  We are especially
interested in a man called John Guy and his part in the Troop.

E-mail me at [log in to unmask]

Many thanks
--
kiz Stonell