EAGLE PASS, Texas— The armed militia arrived at the Rio Grande after dark and headed toward a group of 29 migrants who had illegally crossed the river. The migrants had already been stopped by U.S. Customs and Border Protection, constables and National Guard troops.... Under a spotlight, they huddled against a security fence, awaiting a Border Patrol van that would take them to a nearby station for processing. Assembled law enforcement were not fazed to see the half-dozen armed figures emerge f