Project Gutenberg is a website offering free, digitised, out of copyright books to download. It has a few of the famous personal recollections as well as histories and novels.
Typing in "Napoleonic Wars" into the catalogue search box gets you to a page where books are sorted by popularity and include titles by Marryat and Henty and Tolstoy as well as Kincaid and Marbot. Click on "Subject: napoleonic wars" at the top gets you a further 13 titles.
Narrative of the Most Remarkable Events Which Occurred In and Near Leipzig
Adventures in the Rifle Brigade, In the Peninsula, France and the Netherlands
The Memoirs of General Baron de Marbot
Mr. Midshipman Easy
The Two Great Retreats of History
and my favourite, the all-round famous French blockhead, Arthur Conan Doyle's Brigadier Gerard. Hussar dandy, wooer of women, pursuer of glory and thick as two short planks!
Google Books is another source of free online books, but is not as easy to drive, in my opinion, as it also lists ALL books whether in or out of copyright, full text or only snippets etc. etc. You have to use the limits fairly judiciously before you start a search for full text items.
So far I've found a couple that bear examining;
Memoirs of Napoleon Bonaparte v. 2
Recollections of the Peninsula
Annals of the Wars of the Nineteenth Century v.II 1807-1809