What little I can find on this matter point to two primary sources, 'Children of Rust' by Eugénie Faure and 'To Burn in Memory' by Eva Salandré—both long out of print. The first was published in French by a small, now defunct printing house in Paris, but as to the second I can find no mention.
Here are the fundamentals I've been able to assemble from scattered secondary references, starting where the events took place; a town on the western bank of the Rhine, near Strasbourg. Strangely, no record mentions a name. Quite the child of the Industrial Revolution the city itself was built in the 1850s, largely as a Haussmann inspired project fueled by local nobility moving into commercial enterprise.
Naturally this prosperity came to an abrupt end thanks to the Franco-Prussian War, the annexation of Alsace-Lorraine leaving the city to the now destitute working class. By the 1900s the place was ostensibly the spitting image of Ligeia's "Decaying city on the Rhine" as I'm sure Salandré would be apt to remind me in that overwrought prose of hers.
The incident in question is centered on a revanchist movement of disenfranchised youth. Lead by radical students from a nearby university town, they took to calling themselves the 'Les Enfants de la Rouille'—the Children of Rust. Occupation was their weapon of choice, and they had no shortage of viable real-estate. In addition to this they took to a early dadaist form of art-as-agitation.
The records end around May 1908, during which they seemed to have crossed some line of acceptability, bringing the Prussian military down on them in force. The leaders were summarily executed, with the exception of Faure—who crossed the border and later made a name for herself in the Paris art scene. The international community paid little mind; par for the course as few thoughts are spared for the massacre of working class lives. A small diplomatic incident it made, and soon all small concerns would be swept away by the tides of war.
-Weiss, Alena (1939). Letters from Exile.