Here's a little History on the "round brown" that the Drill Sergeants have to wear.
A veteran of numerous campaigns in the field, steep in traditions, and in active service in various styles from 1850 through 1939, the campaign hat is the most appropriate symbol for a Drill Sergeant. The campaign hat appeared on the scene again in early 1964. THe present style of the campaign hat evolved from the straw or felt slough "Hardee Hat" of the 1850's through the center crease designs of the 1880's, to the present day modified "Montana Peak" which was adopted in 1911.
In late 1971, Headquarters, Continental Army Command (CONARC) received approval from the Chief of Staff of the Army for permission to include women in the Drill Sergeant Program. In February 1972, six Woman Army Corps (WAC) Noncommissioned Officers from Fort McClellan, Alabama, were enrolled in the Drill Sergeant Program, at Fort Jackson, South Carolina. Upon graduation, the women were authorized to wear the female Drill Sergeant Hat.
BG Mildred C. Bailey designed the female Drill Sergeant Hat. The design was taken from the Australian Bush Hat. The first female Drill Sergeant Hat was beige in color. The beige hat was replaced by the dark green female Drill Sergeant Hat, however the style remained unchanged. The green hat was put into use January 1983. After the green Drill Sergeant hat appeared, the beige hat was slowly phased out of the system. In 1984-85, a proposal was made for females to switch to the Drill Sergeant Hat worn by male Drill Sergeants. Female Drill Sergeants at Training and Doctrine Command posts opposed this idea. In June 1985, General John A. Wickham Jr., Army Chief of Staff, stated that female Drill Sergeants would continue to wear the original female Drill Sergeant Hat.