There is no 19th Mountain Division in the army, only a 10th, It deploys out of Fort Drum in New York not Fort Gordon, Georgia. The 10th Mountain Division was the first unit deployed after the 9/11 attacks. Horatio's (David Caruso) concern about his son's decision is very real. If the fictional 19th Mountain Division parallels its real life counterpart, it is considered one of the most dangerous units. It's specially trained to function under extreme terrain and weather conditions.