Mackinaw (Jeep Coat) in World War II
The "Coat, Mackinaw, OD", also called the "Jeep Coat" was first issued in 1938 (called the "first pattern"). The Mackinaw had a water resistant cotton duck outer shell with a wool blanked lining. The distinguishing feature of the first pattern mackinaw was that the 30 oz. blanket lining extended visibily over the shawl collar.
The coat is double breasted and held closed with two rows of three buttons each, and a cotton cloth waist belt with metal or plastic buckle. It was longer than the M41 Parsons Jacket, typically coming to mid-thigh. Below the belt were two flap-front pockets, and it had wide cuff straps.
Labels in these coats will read Stock No. 55-C-33130, Spec. No. 6-104A Dated 2/2/38.
Second Pattern 1942 Mackinaw (Jeep Coat)
The second pattern Mackinaw was very similar to the first, except the wool lining did not extend onto the shawl collar, as in the top photo on this page. Other differences: khaki color cotton poplin shell, lighter, more flexible and comfortable to wear. The inner lining was 26 oz. wool instead of 30 oz.
Third Pattern 1943 Mackinaw (Jeep Coat)
The third pattern can be visually distinguished because it has no belt and the rounded collar was replaced by a notched collar. The shell is olive-drab colored cotton poplin and the chest and shoulder widths were enlarged to permit it to be worn over layers of other clothing. The development of the superior M-1943 Field Jacket caused the third pattern Mackinaw to be a limited standard item that was dropped when supplies were exhausted.