Catapults and Spring Guns. The Tactical Imperative.

One of the many challenges confronting the BEF as trench warfare became established, in early 1915, was how to deal with enemy positions 50 to 200 yards from the parapet of their fire trench. This included German sapheads in No Man's Land, their front-line wire and parapet, and support trenches, as well as machine gun positions. Occasionally, with much effort, a Field Gun would be dragged into a prepared position in the front line to fire a few rounds at a particularly annoying machine gun before being hastily withdrawn but artillery, with its flat trajectory, while useful in attacking targets deeper in the German defences, was a double edged sword when brought to bear on close targets for the blast radius of an exploding shell acted indiscriminately, spraying friend and foe alike with shell fragments, dirt and stones.

Rifle grenades were another possibility, but at this stage of the war, they were few with an unreliable fuse, and while the Sappers and Miners of the Indian Corps were steadily improving the performance of their trench mortars, there was, as yet, no means of manufacturing them in sufficient numbers to supply other Divisions in the BEF.

There were alternatives.

Given the relatively short distances involved, mechanical bomb throwers powered by springs, elastic ropes, or compressed gases offered a practical means of throwing a bomb farther than by hand. Throughout 1915 and into 1916, the French, German, British, and Austrian armies invested heavily in such devices.

The Germans, like the British, appear to have favoured bomb throwers derived from the medieval trebuchet or catapults powered by springs or elastic ropes. One of the most successful French models was based on the medieval crossbow. Whatever type was employed, the infantry on the receiving end heartily disliked these silent weapons of destruction, as revealed in a letter written by Alan Seeger in March 1915,

As if the menace of having the trench blown up at any moment under their feet was not trial enough, the proximity of the lines at this point subject the French soldiers to the fire of the “Minenwerfer” or bomb thrower, these engines of destruction are one of the several novelties the German provision has introduced into the present war. The projectiles, as I understand it, are thrown from a spring gun, and not by explosive force, so that there is no explosion on leaving the cannon. A sentinel with a whistle stands in the French line, whenever he sees one of these bombs arrive, he gives the signal and anybody who is outside in the trenches dives into the nearest shelter at hand till the terrific explosion that they produce is passed. Fortunately, the fire of these machines cannot be trained with much accuracy.

Bomb throwers, as items of ordnance used in trench warfare, have not been treated well by historians. Dismissed as ‘Heath Robinson’ items of equipment, the negative remarks about their effectiveness started early, with no less a person than the Official Historian, who, in all probability, had never seen one in action,

As a substitute for trench mortars, among other devices, catapults actuated by a very strong spring were tried. They sometimes threw a hand grenade 40 to 50 yards but occasionally sent it straight up into the air to descend upon the mechanism. They were hard to conceal, and being impartial in action did not find favour with the troops.

A similar prejudice is still encountered among some of today’s writers on trench warfare.

In my opinion, these negative attitudes derive from inappropriate comparisons with trench mortar, an entirely different type of ordnance with its own distinct tactical role in trench warfare. To dismiss trench catapults as ‘mickey-mouse’ bits of kit begs the question of why the War Office, throughout 1915, issued thousands of them, along with over a million bombs delivering a range of munitions, such as high explosives, smoke, and chemicals, and why the French and German armies were prepared to make a similar level of investment in their models of the mechanical bomb thrower. It is helpful, when trying to place bomb throwers within the context of this early period of trench fighting, not to think of them as ersatz trench mortars, but as specialised ordnance with a specific role in the tactical armoury of the infantry.

When first introduced, their short range, usually 200 yards or less for a bomb thrower powered with springs or elastic ropes, was not a severe disadvantage, as they were mainly employed to deal with that transient issue that characterised trench warfare in 1915, the relative closeness of the enemy defences. As we move into 1916, the utility of mechanical bomb throwers decreases as the nature of the battlefield changed because of the French battles of 1915. Following the introduction of improved cooperation of artillery and infantry on the opening day of the Second Battle of Artois, the French infantry nearly broke through the German positions on Vimy Ridge, a near success that demonstrated to the Germans the folly of concentrating their defence on a single front line, and led them to take their first steps towards developing an in-depth defence strategy. The trenches moved further apart, a process accelerated following the introduction of poisonous gas, as this gave more time to spot its release and for the concentration to fall as it wafted across No Man's Land on the breeze. The front line defences now consisted of two or three lines of trenches widely separated with important defensive assets, such as machine guns, moved further back into the defensive network, all of which significantly reduced the number of targets within the range of a mechanical bomb thrower, and by the summer of 1916 trench catapults were redundant, superseded by trench mortars with their longer range and higher payloads of explosives.