Primitive indirect fire, in which guns took on a target they could not see, had been employed occasionally, with stakes or other markers linking the guns to their target.
'... for an attack to succeed, the enemy’s barbed wire ... had to be cut.'
In the 1890s the development of the dial sight enabled guns to be pointed towards a target identified on the map, whose range could be calculated from range tables. Forward observers could send fire control orders back to the guns firstly by semaphore flags but soon by telephone and latterly by radio.
Powerful though the new high explosive shells were, an enemy who was well dug in was hard to destroy. And for an attack to succeed, the enemy’s barbed wire - coil upon coil in front of his trenches - had to be cut.
The infantry might have to do this with wire-cutters, but artillery could be quicker and more effective – if, that is, its fire was properly controlled. Skilled observation officers could cut barbed wire with shrapnel, but high explosive, when eventually fitted with a fuse that burst when it grazed the surface of the ground, was much better.
In August 1916 Lieutenant Julian Tyndale-Biscoe was FOO (Forward Observation Officer) for a battery of 18-pdrs on the Somme. He describes how:
A day or two later, we had orders to cut the German wire. The Captain went down for the first half of the day, and I did the second half. It was ticklish work, since our guns were so close that the shells, to be effective, had to burst [they were using shrapnel] about three yards over our heads. The two signallers and I were in a front sap which had been cleared of Infantry as there were bound to be some short bursts which might spray the place.
Later on, the Infantry came into the sap, and so, to avoid casualties, I had to change to H[igh] E[xplosive] that only burst on impact. It was not so effective in cutting the wire, blowing it up and knocking it down again. All went well for a bit. Beautiful bursts right into the wire. The signaller each time reported ‘Battery fired’, and the next moment – bang – up went the wire. We could not hear the shells coming because, with the very close range, they travelled faster than sound.
Suddenly, with the next salvo, I was caught in the back with a clod of earth and thought one of our shells had burst short. We were about to continue when, to my surprise, I saw at my feet the shell lying unexploded ... It had apparently hit the ground behind me and hurtled on base first, hitting the parapet, after ripping my gas helmet from my side, and dropped into the trench.
Julian Tyndale-Biscoe, Gunner Subaltern
Shells frequently failed to explode, often because the rifling of the gun which fired them was worn, so that instead of spinning straight they tipped over and over in flight and failed to land nose first, and often because fuses, mass produced as swiftly as possible, were faulty. Unexploded shells still litter the battlefields of World War One.