The M-51 field parka was issued to U.S. military personnel beginning in 1951, updated from the Korean War-era M-1948 parka and designed for sustained cold weather field operations. The "fishtail" name refers to the distinctive rear he;m the back of the parka has a longer tail section that can be snapped up between the legs to prevent wind from entering from below during movement, or left down for additional leg coverage during static positions. It preceded the M-65 field jacket and remains a recognizable piece of U.S. military outerwear history.

The fishtail flap is the defining feature of the M-51 design, the elongated rear hem that extends below the standard hem length. Two snap closures allow the fishtail to be snapped up between the legs, converting the parka from a standard coat silhouette to a configuration that prevents wind from entering at the back hem during movement. This is particularly useful in cold wind conditions while marching or working in exposed positions. When not needed, the fishtail snaps down for standard coat wear.

Yes. The Rothco M-51 Fishtail Parka includes a polyester button-in liner that adds significant insulating value to the cotton shell. The liner buttons around the interior of the parka shell at the collar, front, and hem. With the liner installed, the M-51 system provides cold weather performance appropriate for sustained field use in winter conditions. Without the liner, the cotton shell provides wind and light weather resistance appropriate for cool to moderately cold conditions during active movement.

The M-51 is longer than the M-65;5, it extends to mid-thigh compared to the hip-length M-65, providing more coverage for the upper legs in cold conditions. The M-51 uses a cotton outer shell while the M-65 uses a cotton/nylon blend. The M-51's fishtail design is distinctive and recognizable as a specific era of military history. The M-65 system, with its removable liner, offers comparable warmth in a shorter, more mobile package. Both use button-in liners for adjustable warmth. Choose the M-51 for historical authenticity and more coverage. Choose the M-65 for the more modern military field jacket silhouette and greater versatility.