Auto-translated
Okay, let's think about it. If he was born in 1782, then the battle in which he was captured must have taken place sometime around 1800. Most likely, it was during the reign of Peter the Great (but, of course, Peter the Great is incorrect, as he was never captured).
What battles were there – the Great Northern War, Azov, and something else, I don't remember anymore.
Mazepa, Khmelnytsky – I don't remember anymore who of them was active during that period and who wasn't. But most likely, it's not them.
There was also Charles XII, he was indeed captured; Ment remembers, but I don't remember his name, other than "the conqueror."
And what does choral singing have to do with it? Perhaps it was some kind of church figure, but then I can't name him.
Although, there it is, it clearly states that it's about the Battle of Poltava, and the other wars are irrelevant.
Let's assume that this Vasya was captured and began teaching choral singing.
The traitor of Poltava (if we assume that we shouldn't name him by name – it's completely off).
Added 5 minutes later
Let's say it was King Charles – as a version in my favor.