Swarthmore College has a special collection of peace posters, which I
believe covers quite a span of years and lands.  I don't know if it's ever
been exhibited.

K=E4the Kollwitz was an anti-war visual propagandist in 30s Germany.  There
is at least one English-language publication of her works, and it's likely
they have been exhibited.  Her "Seed Corn Must Not Be Ground" (English
translation) drawing of a woman sheltering children from death overhead is
the most eloquent anti-war statement I have ever seen!

You might also contact The Peace Museum.  The last address I have for them
is 350 W. Ontario St., 4th Floor, Chicago, IL 60610.  Others on Museum-L
may have a later way to contact them.

Happy searching,

Tom

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