Watch CineCalidad. Based on David Maraniss's book They Marched into Sunlight, a documentary telling the story of two seemingly unconnected events in October 1967 that changed the course of the Vietnam War. Whilst a US battalion unwittingly marched into a Viet Cong ambush which killed 61 young men, half a world away angry students at the University of Wisconsin were protesting the presence of Dow Chemical recruiters on campus. (Storyville)