[Jeff Mc William]

Hi Eddie
Crumbs ... what a question ... there are so many !
I guess it depends, (a) How old is your son ? and (b) Does he want a "gentle introduction" or the "full monty" ?
I don't think any of the following can be classed as "easy reading" but, for the Army, my first choice would be "Military Dress of the Peninsular War" by Martin Windrow & Gerry Embleton, pub. Ian Allan 1974. Apart from the obvious indications in the title, this does give a readable and concise account of the war.
Followed by "The Armies at Waterloo" by Ugo Pericoli, pub Chas Scribner 1973, again a readable and concise account of the campaign. Well illustrated.
Moving on to a more detailed general history, there is of course the 3 Vol trilogy by Arthur Bryant, viz :
"The Years of Endurance" 1793-1802
"The Years of Victory" 1802-1812
"The Age of Elegance" 1812-1822
and of course the classic tomes by Charles Oman (7 Vols), and William Napier (6 Vols)
For the Navy, the only comprehensive title I can think of at the moment is "The Naval History of Great Britain 1793-1827" by William James (6 Vols)
One other title I would strongly recommend would be "Wellington. The Years of the Sword" by Elizabeth Longford, pub Weidenfeld 1969, or a similar work (perhaps more readable) by Richard Holmes, Harper 1996.
There are of course many more books on the subject, but these are the ones I would suggest. I believe all the "classic" titles (ie Oman, Napier & James) have been republished lately, so, if you want to dive-in at the deep end, then these are still available and reasonably priced. Regards. Jeff

PS: Forgot to mention the massive "History of the British Army" by Hon.J.W.Fortescue 20 Vols pub Macmillan 1905. Reprinted by Naval & Military Press (14 Vols) 2004. Individual volumes obtainable to cover the period you wish to have.