People tend to forget that the original Vietnamese Buddhist monk to immolate himself, Thich Quang Duc in June 1963, did so not to protest the war, but to protest the Ngo Dinh Diem regime's treatment of the monks. Diem was Roman Catholic, and something of a goon.

The crisis did eventually lead to Diem's assassination and regime change, so I guess his protest worked.

Herz on the other hand didn't appear to have much effect, since the war lasted another decade.