Mortar, Stokes

Delivery systems were also improved. As early as 1920, experiments with the barrel of the Stokes Mortar enlarged the bore to 4.2 in. in diameter, which increased the range of the mortar from 1100 to 2400 yards. By 1928 this new improved mortar became the standardised weapon for the delivery of toxic chemical agents, as well as smoke and high explosives.7... 

Thb compound was introduced by the Britbh at the l>attte of Loos, Sept. 24, 1915, as a filling for 4.2-in. howitwT shell. It was later also used in 4-in. Stokee-mortar bombs and gas grenades and was the British standard lacrinia<%r throughout the war. 

Stokes Mortar The 4 in. Stokes mortar developed for chemical agent delivery was first fielded by the British in September 1915 at Foos, and was in wide use by the Somme battles of 1916 this represented the first use of projectiles filled with lethal chemicals in World War I. Chemical artillery shells (or projectiles ) and mortars remained in chemical arsenals throughout the twentieth century. During World War I, the Germans produced chemical agent-filled projectiles for 77, 105, and 150 mm artillery pieces,... 

The 4 in. Stokes mortar developed for chemical agent delivery, first fielded in September 1915 at Loos this represented the first use of projectiles filled with lethal chemicals in World War I. 

Fig. 1.31 From left to right a Livens container (phosgene), a 4 Stokes (Mortar Bomb (chloropicrin) and a 6" shell (mustard gas), found buried at Bramley in 1987 (reproduced with permission of the Chemical Defence Establishment, Porton Down). They all exhibit an advanced state of corrosion.

The Battle of Arras also saw the widespread use of the Stokes Mortar. Like the Projector, its design was extremely simple a steel tube raised at an angle by two struts. It fired four-inch mortar bombs, each containing two litres of gas. A well-trained crew could fire fifteen bombs and have them all in the air before the first one hit its target, with pin-point accuracy, as much as 1,000 yards away. 

Daily operations were carried out by personnel from the U.S. Army ECBC. The initial two phases of operations were work-up trials and developmental testing. During these operations, two 4-in. Stokes mortars filled with phosgene and eight 155-mm projectiles filled with phosgene were destroyed. The next phase of operations was termed the operational testing It called for the destruction of 30 155-mm projectiles filled with phosgene. One additional munition was destroyed, for a total of 31. The operations were carried out on April 21, 22, and 23, 2008, with 10, 10, and 11 detonations carried out on each of these days, respectively. The operations proceeded fairly smoothly. The... 

The EDS-1 has an inside diameter of 51 cm and is designed to handle three common munitions a 75-mm artillery shell, a 4.2-inch mortar, and a Livens projectile. It has been used to dispose of a 4-inch Stokes mortar and a M-139 bomblet, as well as nonexplosive cylinders. 

British 4-in. trench mortars, called Stokes mortars (Figure 2-11), provided a solution to some of the problems with Livens projectors. The Stokes mortar did not require extensive preparation and could be moved as needed. Since it was not rifled, the range was only 1,200 yd, which meant about a 14-second flight time. The small size of the shell only held about 6 to 9 lb of agent, but experienced gunners could fire 25 rounds per minute. American troops used both Livens projectors and Stokes mortars during the war. Ordnance officers tried making their own Stokes mortars, but none reached the front before the end of the war. 

Fig. 2-11. A complete Stokes mortar with ammunition and accessories for firing. Photograph Chemical and Biological Defense Command Historical Research and Response Team, Aberdeen Proving Ground, Md.

Fig. 2-17. An experimental 4.2-in. chemical mortar, showing (1) the standard, (2) the barrel with the shock-absorbing mechanism, and (3) the tie rods connecting the standard to the baseplate. This weapon differed from the Stokes mortar, its predecessor, in that it was easier to set up and it was rifled the spiral grooves can be seen on the inside of the barrel at its muzzle. Photograph Chemical and Biological Defense Command Historical Research and Response Team, Aberdeen Proving Ground, Md.

During the 1930s, the CWS stockpiled the chemical weapons used by World War I ground forces in preparation for a future war. These were primarily Livens projectors, Stokes mortars, and portable cylinders. In addition, there were chemical shells for 75-mm, 105-mm, and 155-mm artillery pieces (Figures 2-22 and 2-23). 

Nitrostarch was used as an explosive because it did not use the same precursor chemicals as TNT or amatol. The Trojan Powder Company at Allentown, Pennsylvania, produced up to 1,720,000 pounds per month. It was used in the 3-inch Stokes mortar and in hand grenades. DuPont also made a form of nitrostarch called grenite. Nitrostarch is a flour-based explosive often mischaracterized by EOD persoimel as a flour-filled inert round instead of a high-explosive round. 

A 1923 list sets the war reserve CWM at, White Phosphorus 500 tons. Titanium tetrachloride 100 tons. Phosgene 192 tons, Mustard Gas 60 tons. Chlorine 200 tons, Chlorpicrin 40 tons. .. Shell 4 Stokes Mortar, complete 188,000, Livens Projectors 25,000, Shell, L.P. complete 40,000, Cylinders, chemical, portable 25,000, Candles, smoke 75,000, Candles, toxic 15,000, Candles, lachrymatory 25,000, Arsenious oxide 100 tons. .. Sulphur monochloride 2,000 tons. .. Hexochlorethane 100 tons. While this is substantial and frightening, it is considerably less than the material known to have been on hand at the end of the war, particularly the shells and smoke candles. The author believes that the balance was buried or dumped at sea during the years following World War I. 

At the end of World War I, there were four million shells in the United States inventory. World War I ordnance such as the Livens projectile and Stokes mortar were outmoded by World War II, resulting in burials and dumping. Leaking ordnance was a continual problem. Add to that the 1,343,728 World War II chemical bombs, and the 13,550,613 World War II chemical mortar rounds not used in World War II, and the probability of substantial buried chemical weapons becomes a certainty, in addition to the tremendous numbers of currently stockpiled ordnance. Also, even current inventory ordnance would have an occasional leaking or damaged munition. In addition, experimental ordnance, grenades, rockets, candles, spray tanks, smoke pots, and cylinders are also burial candidates. Where is the question state and local regulators need to repeatedly ask. 

Photo 20 shows a stokes mortar found at the AUES site, one of the typical sort of weapons found at such sites. 

There were many shells fired during the dispersion testing that must have left many isolated dud or UXO rounds. For example, on fired Stokes mortars at Camp Simms several unexploded (dud) shells were found resulting from failure to detonate on impact. A similar number of exploded Stokes mortars were also found. Although the final numbers are not in yet, an approximate 50% dud ratio is emerging. Similarly, one of three Livens projectiles was a dud. This is extremely high, most likely due to the early developmental stage of the mortar at this time. 

After completion of the preliminary testing, tests of the EDS-1 with containers and munitions filled with the chemical agents phosgene (CG), sulfur mustard (HD), and sarin (GB) took place between late November 1999 and November 9,2000. For phosgene, 11 items were tested four cylinders and seven 4-inch Stokes mortars. For mustard, 14 items were tested two cylinders, seven 4.2-inch mortar rounds, and five 4.5-inch projectiles. For sarin, one steel cylinder containing 1.3 pounds of agent was tested (U.S. Army, 2000). 

In 1916 the British introduced a new means of projecting gas, the 4-inch Stokes mortar, developed from the 3-inch version of this weapon, which had been the standard mortar in the British Army. Because of their inability to manufacture gas shells, the British first used the mortar to fire improvised smokes and incendiaries. The Stokes gas shell, or bomb, as the British called it, contained six pounds of agent as compared to three pounds for the British 4.5-inch heavy howitzer shell. 

Its 1,000-yard range was adequate for situations in which opposing trenches were not far apart, and its accuracy, while not pinpoint, was good. Crews were capable, under combat conditions, of firing fifteen rounds per minute, a rate of fire more rapid than that of the howitzer. Still, the Stokes mortar had its limitations. 

The British and French had adopted a tactic of gas warfare dependent on overwhelming the enemy with vast quantities of toxics. The massive cylinder attacks of the British and the artillery barrages of the French met this requirement. The Stokes mortar also could have met such requirements for targets less than 1,000 yards distant, but the number of mortars, shells, and crews necessary was beyond the capacity of the Allies at this time. The need was for a simple inexpensive projector with a longer range and a larger capacity shell. Such a projector was invented almost by accident. 

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