The 108th Infantry Regiment is mentioned only in Fallout 4.
Behind the scenes
The following is based on unverified behind the scenes information and may be inaccurate.
The 108th Infantry Regiment is a real regiment of the New York Army National Guard, created in 1898. The 2nd Battalion currently serves as its only existing battalion.
End of information based on unverified behind the scenes information
↑ Cut Sanctuary Hills terminal entries: "7:00 pm - Drinks with Fox Company Go 108th! (Probability of us getting drunk and singing "The Snows of Anchorage" 5 times - 110%)"