This is an original French production U.S. 1918 mark 1 trench knife. These were made by Au Lion in France.
Serial number stamped on the right ricasso. Double sided blade finished bright. Brass handle. Left ricasso stamped with the "Reposed Lion / AU LION". Marked "U.S. 1918" on right side of grip.
Comes with a leather scabbard instead of the normally seen metal one.