In August 1944, as World War II raged, a battalion of well-trained Army artillerists were suddenly switched to a different weapon, the stubby but lethal M2 81-mm mortar, and provided just 60 days of training on how to wield that gun on the battlefield. By December they were dug into trenches in the French Vosges Mountains, facing a brutal winter and a determined foe. My father served in a crew of the 99th Chemical Mortar Battalion, which by war's...