Letter from the Duke of Wellington to the British Foreign Office (1809)
wellsoc.org
Slightly more readable link: https://cns.gatech.edu/CNS/GTaccountProcs.pdf
wellsoc.org
E.g. here he's complaining to the undersecretary of state:
https://archive.org/details/dispatchesoffiel10welluoft/page/...
Here (and a few lines on the page before) is a long letter with his advice on how to reconstitute the (allied) government of Spain:
https://archive.org/details/dispatchesoffiel10welluoft/page/...
[1] I am sure this is not actually the right term. I do not care.
Instead it’s the more wordy “created a duke”, since his status was both created and granted to him. The title “Duke of Wellington” was expressly created for him.
Fun fact, he should have been “Duke of Wellesley”, but his elder brother, Richard Wellesley, had already been made Marquess Wellesley.
Since the peerage from Viscount to Marquess to Duke would ended up with two brothers potentially sharing the same title, they chose to give Arthur the title Viscount Wellington, from the town where the family heritage was connected to.
Therefore his title peerage line:
Viscount Wellington -> Earl of Wellington -> Marquess of Wellington -> Duke of Wellington
He was also technically a Baron before Viscount but he received that peerage the same day as his Viscount title.
Outside British peerage he held some other cool honors and titles. As well as being the Prince of Waterloo in Belgium the the Netherlands, he was granted the honor of “Knight of the Golden Fleece” in Spain, “Knight of the Black Eagle” in Prussia, and my personal favorite was “Knight of the Elephant” in Denmark.
In the UK we have lots of reminders of him namely because of the large number of pubs called “The Duke of Wellington”.
Don't know whether that's true or not (that the Duke of Wellington said that) but... One year later (1815), he handed the french's arses back to them big, big, big, times at Waterloo.
Basically the battle of Waterloo (a few kilometers away from where I was born) is considered the time when the UK overtook France as the world's number one superpower.
Since then both have only ever been falling in the rankings and it doesn't look like that fall is going to stop anytime soon but that's another topic.
But unlikely a result of said battle, rather the instability of politics in France.
Us British oft think of Waterloo as a great victory, although the circumstances, participants and objectives were pretty nuanced. Wellington himself rejected congratulations and thought battle to have very high cost.
That's an anachronism, from the 19th to mid-20th century there were just "great powers", not perfectly matched but considered to be in the same class. The Ottoman empire falling off the league ("sick old man") was a bit of a shocker.