The "charm" worn as a protective amulet, dates back to ancient times. Silver charms, worn as sentimental mementos, can date through the 19th century.
Charm bracelets, with thematic forms, were a 20th century trend which reached a height of popularity in the 1950's and 60's.
Charms were manufactured by the thousands on both sides of the ocean. I don't know if there were charms made to commemorate WWII bombing sites.
Tourist charms for example ; A charm produced in Birmingham, (a traditional manufacturing area in England) might have been commissioned by a gift shop affiliated with an Irish castle or Scottish ruin. Pictorial tourist guides may help identify your charm.
In the fall, 2001 issue of "Adornment The Newsletter of Jewelry & Related Arts," there was a great cover article entitled, "The Charm Bracelet in Mid-20th century America", by Yvonne J. Markowitz, "Adornment" can be reached by mail: 133 A North Ave, New Rochelle, NY 10804 U.S.A., Phone/Fax: 914-637-0087, E-mail: firstname.lastname@example.org