Between 1750 and 1815 fear of invasion by the French prompted the British to organize and deploy land forces in an unprecedented way.  The country normally looked to its powerful navy as its first line of defense. During this period, the American War of Independence, French Revolution and Napoleonic Wars meant the threat of invasion was heightened.  Sussex with its low lying beaches and proximity to France was seen as especially vulnerable.

At this time, there were three distinct groups of armed land forces.  “The regular army was a permanent paid force of men serving at home and abroad. The militia was a paid force of infantry raised in the counties by ballot; it was usually called upon to serve full-time in wartime only, and served only in Great Britain. The volunteers were men living at home who volunteered to serve part-time in their own areas.” 
(Ann Hudson, Volunteer soldiers in Sussex during the Revolutionary and Napoleonic Wars, 1793-1815, Sussex Archaeological Collections vol. 122, pp. 165-81) 

In 1779, John “Mad Jack” Fuller, at the age of 22, was captain of a light infantry company in the Sussex Militia. A regiment of the Sussex Militia had been quartered in Brighton, but their duties were in light and so, the officers could frequently be ,”seen at most hours of the day on the Steine, strolling beside the lady visitors, while the ranks entertained their maids in some less fashionable spot”. (Margaret Barton & Osbert Sitwell, Brighton, 1935, pp. 82 -84) 

Diarist Frances “Fanny” Burney records her impressions of the young captain who she encountered when staying with Henry & Hester Thrale in Brighton from 23-25 May, 1779. “The Sussex militia, of which the Duke of Richmond is Colonel, is now here. Mr Fuller, a very intimate young friend of Mr Thrale, who is Captain of a Company belonging to it, Dined with us.  He is a young man of a very large fortune, remarkably handsome, and very gay, sensible, unaffected and agreeable.” 

Fuller boasted of having, "75 servants, all in my livery”, which Burney took to mean the men under his command. 

Burney describes: breakfasting with Fuller in his apartment on the Steyn (sic);  going to the parade to see the muster; dining with Fuller & the Thrales at the home of Major John Baker Holroyd also on the Steyn; a trip to Lewes to visit the Shelleys, cousins of Hester Thrale, where they meet Fuller awaiting  a meeting of militia officers with the Duke of Richmond. 
(Frances Burney,  Journals and Letters, pp. 116-119)

Read excerpts from her diary here. 
The menace of a potential French invasion intensified between 1793 -1815 during the Revolutionary and Napoleonic Wars, interrupted for a brief fourteen months by the Treaty of Amiens (1802 – 1803).

On 1 May 1794, a meeting of prominent people was held in Lewes and it was resolved that volunteer infantry and cavalry troops were to be raised for the defence of the county of Sussex. By the end of 1795, nine troops of Sussex Gentlemen and Yeomanry Cavalry were raised, followed by an additional four in 1798. 

Jack Fuller raised the Brightling Troop, detached at Rose Hill, on 27 June 1798.  It, like many others, was disbanded in 1802 with the signing of the Treaty of Amiens. Fuller's cousin John Trayton Fuller, referred to by Burney as, ”a heavy Sussex Headed young man”, raised a troop at home in East Grinstead and one at Eastbourne.
Of the volunteer corps, the Gentlemen and Yeomanry Cavalry was the most prestigious and attracted “well off” and aristocratic members. It was thought that gentlemen of high local standing would work better together and have an easier time imposing discipline on their men. 

After basic training, the volunteers would engage in mock battles using guns loaded with blanks. Both sides would often sit down together to dinner which would include liberal amounts of drink.

“Several of Fuller’s letters to Egremont have been preserved.  In a correspondence dated November 30, 1799 and sent form his Devonshire Place address, Fuller acknowledged the receipt of £120 (£ 3 per man) to equip his troops and in 1801 he informed his Lordship that his troop was again up to its original establishment of 40 men, comprising one lieutenant, one trumpeter, three sergeants, three corporals and 32 privates.”  
(Geoff Hutchinson, Fuller of Sussex: A Georgian squire, pp. 39-42)
Sussex Troops of Gentlemen and Yeomen Cavalry

Petworth Troop, raised by 3rd Earl of Egremont, 23 June 1794
Henfield Troop, raised by William Campion, 23 June 1794, disbanded by 1824
West Hoathly Troop, raised by William Sewell, 23 June 1794, disbanded by 1824
Forest Row Troop, raised 23 June 1794, (det at Ashdown), disbanded in  1802
Hastings Troop, raised 26 July 1794, regimented by 1802, disbanded by 1824 
Rye Troop, raised 31 July 1794, disbanded in 1802 
Midhurst Troop, raised by William Stephen Poyntz,  24 Nov 1794 (det at Cowdray)
Lewes Troop, raised by George Shiffner, 3 June 1795 (det at Coombe) 
Parham Troop, raised by Sir Cecil Bisshopp, 8 Oct 1795, disbanded 1815/16
Chichester Troop, raised by George White Thomas, 15 June 1797 (det at Watergate), disbanded in  1802
Artillery Troop, raised 15 June 1797 at Goodwood, disbanded in 1802 
Eastbourne Troop, raised by John Trayton Fuller, 20 June 1798 (det at Willingdon), disbanded by 1824 
Ashburnham Troop, raised by Viscount St. Asaph, 27 June 1798,  disbanded  in 1802 
Brightling Troop, raised by John Fuller, 27 June 1798, (det at Rose Hill), disbanded in  1802

1779 Map of Brighthelmstone (Brighton)
Charles Lennox,
3rd Duke of Richmond
Uniform of the 
Sussex Gentlemen and Yeomen
Militia & Yeomanry
Sugar & Slaves
Royal Institution
Bodiam Castle
Eastbourne Lifeboat & 
Belle Tout Lighthouse
John 'Mad Jack' Fuller
Sussex Militia and Sussex Troops of Yeomen Cavalry
On the Trail of Mad Jack Fuller  BLOG
Fuller Family of Sussex  GENEALOGY PAGES