The photo shows your button has what is called a self-shank back, which means it is from the 20th-Century (or later). See photos below. Also, it is not an actual Military button.
Important note:
The term "self-shank" back means a 2-piece (hollow) button whose back itself forms the shank (tunnel for the thread), instead of having a separately-made loop attached to the button's back. The two photos show only one of the varieities of slef-shank back. I'll add a third photo to show another variety of self-shank back.