Mariann Wizard reviews Nancy Miller Saunders’ book, “Combat by Trial: An Odyssey with 20th Century Winter Soldiers,” about the historically significant anti-war movement that developed among GIs and veterans of the Vietnam War — and the IVAW, the group that led that movement. Mariann herself was involved in those efforts, along with her vet husband, Larry G. Waterhouse, and she also discusses the book she and Larry wrote together in 1971: “Turning the Guns Around: Notes on the GI Movement.”