This Colt M1911 was shipped to the Ordnance Depot at the Bush Terminal in Brooklyn N.Y. on June 25th, 1918 in a 10,000 pistol shipment.
This particular pistol is what collectors refer to as a "Commercial/Military" or "C/M". These are pistols that were manufactured using readily available Commercial slides to finish the assembly of Military pistols.
During May and June of 1918 it's common to observe pistols that have these Commercial slides with the added "MODEL OF 1911.U.S.ARMY". The right hand side of the slide still wears the original commercial "COLT AUTOMATIC CALIBRE 45".
Military and Commercial finishes were quite different during this time. The frame is finished with what is known as Colt's "Black Army" finish while the slide still has Colt's Fine Brushed blue finish.