A gold oak leaf serves the insignia of rank for Lieutenant Commanders in the U.S. Navy and Coast Guard and for Majors in the Army, Air Force, and Marine Corps. The Navy rank was derived from the phrases “Lieutenant Commanding” or “Lieutenant Commandant” used to describe a Senior Lieutenant captaining a small warship and was introduced in 1862; Navy Officers in the new rank began wearing gold oak leaves on the shoulder straps of coats at the same time. As primarily a land-based force, the Marine Corps followed Army Officer ranks in nomenclature; the Army introduced gold as the single color for Majors in 1872.
The Navy, Coast Guard, and Marine Corps share the same size gold oak leaf rank device for placement on outerwear such as All-Weather Coats, Windbreakers, and so forth. They also follow the same general placement rules: the insignia is centered between the front and rear edges of the shoulder strap of the outerwear, with the outer edge of the device 3/4-inch from the shoulder end of the strap. However, Lieutenant Commanders in the Navy and Coast Guard orient the leaf so that the stem points away from the collar; Marine Corps Majors, on the other hand, wear oak leaves with the stem toward the armhole seam (and, obviously, the collar).