The First World War (on the Western Front at least) can be likened to a siege; the longest siege in history. From its inception at the end of 1914, trench warfare was to characterise the war - so much so, in fact that the term 'in the trenches' was used by soldiers and their families alike as a shorthand for frontline duty. The term trench was to have widespread currency: trench feet, trench fever, trench cough, trench boots, trench coats, in seemed that the term trench could be applied anywhere in order to give items - and ailments - credibility.
So who fought this siege? If it was the infantry - under the direction of the Royal Engineers – who dug the trenches, then it was the artillery who tried to destroy them, deploying latter-day siege engines (howitzers) to reduce the fortifications (the trenches), and allow the infantry (and, it was hoped, the more mobile cavalry) through. It is hardly surprising, then, that postcards of soldiers wearing the uniform of the artillery - and specimens of cap badges worn by artillerymen - are commonly found mementoes of this industrial conflict.
The men of the Artillery were numerous, and were divided up into several branches: the Royal Horse Artillery (RHA) were mobile, as their name suggests, and deployed lighter guns (still used on ceremonial duties today) than those that equipped the Royal Field Artillery (RFA). RFA men like the soldier illustrated manned low trajectory (18-pounder) field guns that were quite forward and in danger of being destroyed by enemy counter-battery fire. Their war was scientific and skilled, and deployed a wide range of missiles: shrapnel, gas, high-explosive. These guns would have to be moved in trying conditions - and horses would do much of the work alongside their human colleagues. The third major branch was the Royal Garrison Artillery (RGA). RGA men served even heavier artillery pieces - howitzers that could lob shells over great distances, their high trajectory ensuring that trenches and their dugouts be obliterated. Such pieces were static, and some were mounted on railway gun carriages.
The badge worn by all artillerymen screams its purpose. The large brass canon, and mottoes 'Ubique' (Everywhere) and 'Que fas et gloria ducunt' ('wherever right and glory lead'), emphasise the universality of the men who manned the guns, during the conflict one contemporary called 'The War of the Guns'. It is still worn to the present day.
Peter Doyle's book The British Soldier of the First World War (buy it now) explores these issues in more; discussion of the Royal Artillery cap badge can be found in his acclaimed British Army Cap Badges of the First World War (buy it here), written with Chris Foster. Both are published by Shire Publications.
The Royal Artillery Museum, Firepower, many be visited here.