Wandering through the chill autumn woods outside Stockholm, a casual American tourist might have stumbled across the 20 goose-pimpled Swedes and Finns and mistaken them for a bunch of overage Boy Scouts minus their marbles. Shivering in skimpy costumes—cotton shorts and shirts and gym shoes—they looked like summer hikers, some two months late, waiting for a tardy scoutmaster to take them home.
But no scoutmaster arrived. Instead, brisk, businesslike officials gave each man a number and a map. One by one, as the numbers were called, each man trotted off by himself, whipped out a small compass, lined up his map and...