The three military fathers sat at the commander's conference table on the U.S. Army base in Germany, pleading for help.

They told the commander that their daughters were among a half-dozen girls sexually assaulted by a boy in their first-grade class at the base school. The principal had known about the boy's behavior for months, they said, but the abuse continued.

The girls' parents had already turned to Army police, military child-abuse authorities and sex-assault specialists. The response throughout the U.S. military's vast support structure was always the same, they said: Sorry this has hap...