Earliest History of the Peninsular War?

I think I have also exhausted all obvious avenues. But I think I agree with @Zack White that it's some sort of semi-official thing, or at least published with authority. But @tomholmberg is probably also correct that it was assembled with the aid of periodicals and a pair of scissors!

I did have search for reviews in The Gentleman's Magazine or similar, as they often come up with books written at the time and sometimes provide clues for authorship, but I couldn't find any.

WorldCat unfortunately provides no additional info.

I wonder if this wasn't basically compilations of documents publicly available, either in gov. docs. or that appeared in works like the Annual Register?

They're all here: https://bit.ly/38CcVjk

The contents seem to be as follows:

1. Policy of the war. Military view of the peninsula. Preliminaries to the operations of the British Army.

v. 2. First British campaign (1808). The convention of Cintra. Restoration of the kingdom of Portugal, on its evacuation by the French troops.

v. 3. The campaign under Sir John Moore, his retreat, and re-embarkation of the British Army.

v. 4. Military state of the peninsula, in 1809. Defence of the eastern frontier of Portugal. Advance of an army under Sir Arthur Wellesley (Marquis Wellington) into Spain. The battle of Talavera.

v. 5. Views of the campaign, of the allies and the enemy. Military-diplomatic negociation of Marquis Wellesley. Retirement of the British Army to the Portuguese frontier.

The volumes seem to have been published between early 1812 (vol. 1 preface is dated 1 Jan 1812) and 1814. I suspect more volumes were planned but didn't get written for one reason or another?

I've just spent a very interesting half-hour skimming the first chapter in Vol. 1 on British military policy... ("colonise Sicily"? Really???)

Oh, this is fascinating. Have found all five volumes on archive.org and having a bit of a lunchtime geek-out. I can't work out where the text might have come from, although the extensive dedication to the Duke of York suggests the author was a fan.

I don't know anything, I'm afraid, but my eye is immediately attracted by the line about the "distinguished military conduct in individuals, whatever their rank in the army". I'd be curious to look at this and see how that is achieved in practice.

This comment won't help much, but T. Goddard had their hand in publishing military works. In 1810 they printed 'The military law of England'. (A pretty decent and useful volume). They described themselves as military booksellers, but I wonder if the anonymity (both of this History, and Military Law) might imply that it's coming from the government?