Army Air Corps Specialist (1st–6th Class)

Twelve enlisted technical specialties — airplane and engine mechanic, aircraft radio operator, parachute rigger, aircraft armorer, meteorologist, aircraft photo tech, aircraft machinist — held by enlisted men ranked Private Specialist (1st through 6th Class).

The Story

You couldn't tell a Specialist from a PFC by looking — same single chevron. Authority depended on rockers granted by post commanders, not the War Department. In 1941 the Army discovered it had thousands of these men in critical Air Corps billets and no way to mobilize the system; the rank died the next month.