I felt my heels and coat-laps peculiar subjects of assault; and parrying off the larger combatants as effectually as I could with the poker, I was constrained to demand, aloud, assistance from some of the household in re-establishing peace.
There are no more uses of "constrained" in the book.
Show samples from other sources
...it is very grievous to be constrained to keep our hands off such a dainty dish as Narnia.
C.S. Lewis -- The Horse and His Boy
It seemed that we were all cloaked in an unwelcome garment of racial difference that constrained, confined, and restricted us.