Until 1903, the United States Army was highly decentralized, with the heads of staff departments reporting directly to the Secretary of War and each department receiving direct funding from Congress. Staff officers in these departments did not fall under the command purview of a single commanding general, but rather reported only to the departments heads. While the independence of the various staff departments did tend to reduce bureaucratic delays within their limited sphere of operations, the lack of coordination and planning between the departments inevitably led to inefficiencies in a variety of areas, from weapons research and acquisition to logistical and operational missteps.
During the Spanish-American War in 1898, the lack of coordinated, centralized planning led to major issues in supply, transportation, and medical services, spurring the creation of a Presidential commission to identify a root cause of the problem; it recommended consolidation of many of the functions of the various departments and bureaus under a single planning authority. This ultimately led to the passage of the General Staff Act of 14 February 1903, which established the position of Chief of Staff of the United States Army and a General Staff Corps comprising forty-four officers assigned to four-year details. Sixteen months later, the second Chief of Staff of the Army, Lieutenant General Adna Chaffee, signed off on the design of the insignia to be worn by officers (Captain and higher) detailed to the General Staff Corps.
When the Department of the Army was created to replace the War Department, the word “Corps” was removed from the designation of the officers detailed to the staff. Today, the device is authorized for wear not only by officers serving on the General Staff, but also to officers detailed to General Staff with troops.