Drones swarmed the museum-grade GAZ-69 trucks. All along the front line, vehicle losses are spurring a swift de-mechanization of the Russian army. A few weeks after first appearing in significant numbers along the front line in Ukraine, Russian GAZ-69 trucks—museum pieces from the 1950s—seem to have participated in their first direct assault on Ukrainian positions. “We are an inch away from the GAZ-69 sturm,” open-source intelligence analyst Moklasen predicted on April 1, using slang for “attack.” They were right. The Thursday assault outside Bilohorivka, at the juncture of Luhansk and Donetsk Oblasts in eastern Ukraine, ended badly for at least...