This is a World War I signal rocket and was fired from a rocket tube to a height of 1,000-1,200 feet. The signal cartridge payload was then automatically ignited and ejected and slowly lowered by a parachute so that the signal burned for about 30-40 seconds. This specimen is marked "Green" on its label and therefore had a green signal.
Signal rockets and resembled ordinary firework rockets and used gunpowder. This specimen has a guidestick socket but lacks its long wooden guidestick. The green light conveyed certain signals by pre-arranged codes. Signals included commands like "Advance to the right (or left)," and so forth. This object was donated to the Smithsonian in 1996 from the U.S. Army Ordnance Museum.
This object is on display in Rockets & Missiles at the Steven F. Udvar-Hazy Center in Chantilly, VA.