NOW A NATIONAL GEOGRAPHIC MINISERIES EVENT ABC News' Chief Global Affairs Correspondent Martha Raddatz shares remarkable tales of heroism, hope, and heartbreak in her account of "Black Sunday"--a battle during one of the deadliest periods of the Iraq war. The First Cavalry Division came under surprise attack in Sadr City on Sunday, April 4, 2004. More than seven thousand miles away, their families awaited the news for forty-eight hellish hours--expecting...