Right, I forgot the poor Franz Werfel (probably the one of her husbands and lovers who was the most clearly "overwhelmed" by her personality) and while she was not married to all the ones I mentioned, she certainly was involved with them.
Everybody knows the Music for the Royal Fireworks and Handel composed several other pieces to celebrate successful campaigns or peace treaties of his host nation (like the Utrecht and Dettingen Te Deum).
There is another composer with several works associated with the wars and victories of a nation not his own (and it is not a borderline case like Handel's who by the time of Royal Fireworks had become naturalized) but joined in a struggle against a common enemy.
I am not looking for the famous one (but the famous one would help one along to the solution) but a fairly obscure one that has a direct connection to both a decisive event and a war hero.
Name the composer, the piece and explain the personal connection.
(hint: there is a somewhat cheesy poem from a later time also referring to that event)
I'd also hope that people who immediately know the answer keep back for a while not to spoil the fun.