The best fun was with Madame Joubert: Miss Wilson was a poor sickly thing, lachrymose and low-spirited, not worth the trouble of vanquishing, in short; and Mrs. Grey was coarse and insensible; no blow took effect on her.
There are no more uses of "vanquish" in the book.
Show samples from other sources
The team vanquished all competition.
You need to vanquish those negative thoughts and think about good things.