a blind or unexploded ordnance (UXO) (the older term, "dud", is discouraged because it implies that the shell cannot detonate.) Blind shells often litter old battlefields; depending on the impact velocity, they may be buried some distance into the earth, all the while remaining potentially hazardous. For example, antitank ammunition with a piezoelectric fuze can be detonated by relatively light impact to the piezoelectric element, and others, depending on the type of fuze used, can be detonated by even a small movement. The battlefields of the First World War still claim casualties today from leftover munitions. Modern electrical and mechanical fuzes are highly reliable: if they do not arm correctly, they keep the initiation train out of line or (if electrical in nature) discharge any stored electrical energy. References Sources Hamilton, Douglas T. (1915). "Shrapnel Shell Manufacture: A Comprehensive Treatise". New York: Industrial Press. Hamilton, Douglas T. (1916). "High-explosive Shell Manufacture: A Comprehensive Treatise". New York: Industrial Press. Hogg, O. F. G. (1970). "Artillery: Its Origin, Heyday and Decline". London: C. Hurst and Company. External links "What Happens When a Shell Bursts," Popular Mechanics, April 1906, p. 408 – with photograph of exploded shell reassembled : A website about airdropped, shelled or rocket fired propaganda leaflets. Example artillery shells for spreading propaganda. Artillery Tactics and Combat during the Napoleonic Wars How does the ammunition of a towed artillery work? – video explanation Artillery ammunition Explosive projectiles Chinese inventions Gunpowder