As I’ve discussed in earlier posts, finding enough guns to arm the A.E.F. during World War I proved a challenge. The Army lacked sufficient quantities of guns in 1917 to meet the massive need. Focusing for this thread of posts on divisional guns, after delays with a domestically designed M1916, the Army ordered the M1897, a licensed produced French gun, into production. Yet even that production fell behind. The only practical solution was the purchase of French guns in France to meet the immediate need.
But the purchase of French guns failed to meet one very important need. Entering the second half of 1917, the Army faced a serious shortfall of training weapons. After all, training artillerymen requires a lot of hands on training. Although the M1902 3-inch gun met this need in part, there were only a few hundred available. It just so happened that the Bethlehem Steel Company of Pennsylvania was already producing light field guns for the British Army. Common sense struck and the Americans would adopt this gun as the M1917.
Back in 1915, British authorities recognized the need for more field guns than possible from English factories. So they contracted Bethlehem Steel in 1915 to production the standard Royal Artillery light field gun – the 18-pdr Quick Firing (QF) Gun Mk I gun. Bethlehem delivered around 850 of these (to go with nearly 8,400 from English wartime production).
A bit about the 18-pdr’s history. Following the Second Boer War (1899-1902), the British sought to replace obsolete field guns then in service. The British chose two calibers – an 18-pdr (84mm or 3.3-inch) gun for the field artillery and a 13-pdr (76mm or 3-inch) gun for the horse (cavalry) artillery. Although both served in World War I, the Royal Artillery found the 13-pdr’s shell too light and it was largely replaced by 1916.
The 18-pdr used a wire-wound barrel. Under that method, construction starts with a thin-walled bore tube, over which the gun-makers wrap wire under pressure. Over the wire is an exterior jacket. Fifteen layers of .04 x .25 inch wire reinforced the breech end of the gun. This process had great advantages in economy and allowed gunmakers to spot flaws in the metal rather easily. Later versions of the 18-pdr, starting with the Mk. II, featured barrels produced with hydrostatic pressure, to speed production. But Bethlehem used the original wire-wound construction technique.
The breech block of the 18-pdr was a standard hinged interrupted screw. Nothing fancy or particularly ground breaking.
The recoil system used a hydraulic-spring system all housed in a set of tubes mounted above the barrel. When fired, the recoil motion of the gun pulled a piston through an oil filled tube inside the recoil mechanism. Oil flowed through holes in the piston, resisting the rearward motion of the gun and at the same time compressing the springs. When recoil stopped, the springs then forced the gun back forward and the reverse motion of the oil ensured the gun didn’t “slap” back into place. Often a crews wrapped a rope around the outside spring housing for additional protection of the tube (mostly against dents that would block the motion of the springs).
In action two problems arose with the recoil system – fluid loss and weakened springs. The base system used just enough hydraulic fluid (the oil) to work the system, but after frequent firing (i.e. at combat rates), the system leaked enough to reduce the cycling of the recoil force. Furthermore, the springs often lost their power after extended used, forcing crews to “crank” the gun back into firing position by hand. The British temporarily solved the first problem by introducing a box reservoir (seen to the left of the diagram above and called a “gravity tank”), with an armored housing for protection. The immediate solution for the second problem involved more frequent spring replacements.
Most Bethlehem guns had the reservoir attached to the recoil system. However starting in November 1916, British guns were refitted with the “permanent” solution – a hydro-pneumatic system replacing the springs entirely. This setup fit neatly within the existing spring housing and could be installed in field shops. Most British 18-pdrs received this refit, but few if any American guns did.
The 18-pdr used a rather typical pole trail, not unlike that found on the American M1902. This limited elevation, but for the Americans training to use the M1897, this was not an issue. Later British versions of the 18-pdr introduced a box trail that allowed the gun to elevate higher. The British gun also used a panoramic sight, also similar in concept to the M1902′s.
Going back to the “common sense” of 1917, the Artillery branch pushed hard for allotments of these 18-pdrs from Bethlehem. At the time, the company offered to produce the gun in either 3.3-inch (the standard British 84mm) or 3-inch caliber to meet American needs. While the artillerists were happy with the 3-inch option, the Ordnance Branch with support from the A.E.F. insisted on 75mm. Although the Army ordered the first M1917s from Bethlehem in May 1917 the change of caliber and bureaucratic challenges delayed the first deliveries until January 1918. Bethlehem delivered 800 guns by year’s end. Anticipating needs for the planned 1919 offensive, Bethlehem had contracts for over 1500 more guns – cancelled with the end of the war.
The successful adaptation of the 18-pdr stands in sharp contrast to the delays seen with the M1897 and M1916 guns. Arguably the M1917 / 18-pdr could have equipped American batteries in 1917 either in its original caliber or 3-inch version. Even the 75mm M1917 could have preceded the M1897′s arrival in France. But the Ordnance Department, with no small influence from the French, felt the 18-pdr an inferior gun. They saw faults with the 18-pdr’s spring recoil system, wire wound barrel and pole-trail carriage. Ordnance officers wanted to introduce a British designed hydro-pneumatic recoil system and a modified carriage, but the artillerists objected to any delays in production. Bureaucracy, more so than technical issues or manufacturing concerns, delayed the M1917.
In closing, enjoy a British 18-pdr firing blanks.
Four rounds, in under 30 seconds, with demonstration safety precautions.