On page 200 of Volume I. you were told how a howitzer differs from an ordinary field gun. Let me repeat what I then said. The great difference between the action of an ordinary gun and that of a howitzer is the difference between a boy throwing a stone at a mark which he can see, and the same boy lobbing a stone over a wall so that it will fall on something hidden from his view. The ordinary field gun has a long, flat sweep of fire, and is therefore unable to shoot over hills, trees, or houses, or to drop shells on men lying close behind a bank or in a deep, narrow trench.
Look at this little diagram. A howitzer, A, is firing at a fort, B, from the other side of a hill. The howitzer is invisible from the fort, and the men firing the howitzer cannot see the mark at which they are aiming. But a man on or above the hill can see the fort easily, and can so direct the fire of the howitzer that it can lob its shells over the hill and drop them directly on the fort. The guns of the fort are incapable of hitting the howitzer. The shells which they throw pass right over the hill, and fall a long way behind it.
Until recently the fortress gun was master of the howitzer, for several reasons. The howitzers then in use were small, and their range was much less than that of heavy guns mounted in forts. No matter how carefully the howitzers were concealed or how frequently they were shifted about, they were sure sooner or later to be "spotted" from the fortress, and put out of action. The explosives which were then used in the howitzer shells were not sufficiently powerful to destroy the steel and concrete of the forts, and there was much difficulty in discovering, whether the aim of these high-angle guns was true.
The Austrian and the German General Staff had studied all this very carefully, and they had come to the conclusion that howitzers could be constructed of such a size that they would be more than a match for fortress guns. Former howitzers were 6 inches across at the mouth; but before the war the Austrians built howitzers of from 11 to 12-inch calibre. This doubling of the calibre meant that the new weapon was eight times as powerful as the old one. Such howitzers could throw their shells from an immense distance, and could take advantage of steep cover so far off that the fortress guns could not reach them. Though the new howitzers were so heavy, they were capable of being moved from place to place as soon as they were "spotted".
Not only was the howitzer made much bigger than formerly, but new and very powerful explosives were discovered, and huge shells were filled with them. Experiments led the German Staff to believe that these explosives would utterly destroy the forts, no matter how solidly they might be constructed. How to aim these howitzers correctly was the only remaining difficulty. Aeroplanes and balloons solved the problem. Observers could fly high enough to see the forts, note where the shots fell, and signal to the gunners so that they could find the exact range.
The Germans believed that no fortress along the line of their advance could long resist their big howitzers and high explosive shells. The French, on the other hand, thought that such ring fortresses as those at Liége, Namur, and Verdun could hold out for a considerable time. During the Russo-Japanese War of 1904-5, Port Arthur, though attacked by howitzers, held out for eleven months. The French saw no reason why their forts should not resist for several weeks at least.
From what you have read in the former volumes you know that the German theory was right, and that the French theory was wrong. Liége, Namur, Maubeuge, and Antwerp all fell before the high explosive shells of the huge howitzers in an astonishingly brief time. Verdun did not fall, it is true, but this was because the French turned it into a new type of fortress altogether. They made field works at a considerable distance from the old forts, and moved out the heavy guns to advanced trenches. Rails were laid down so that as soon as the guns were "spotted" they could be moved to new positions at short notice. Thus, as I told you on page 280 of Volume II., instead of fixed forts, each, say, mounted with ten heavy guns, these same ten guns were "dotted here and there in trenches rapidly established in one place and another, along perhaps half a mile of wooded vale, and free to operate, when they moved, over perhaps double that front." This is the German theory of fortification, and Verdun was saved because the French adopted it.
Another theory of the German Staff was that high explosive shells could be used with great effect not only against fortresses but against troops in the field. In former wars shrapnel[4] was largely used, but in the present war the Germans believed that high explosive shells would be more effective.[5] Modern armies, as you know, "dig themselves in" whenever they can, and fight from trenches. Against troops in deep trenches with good head-cover shrapnel is not very deadly. When trenches have been occupied for some time they become little fortresses, with strong parapets and entanglements of barbed wire in front of them. Before sending infantry to attack such trenches, the Germans determined to fire high explosive shells at them, so that the barbed wire would be torn away, the parapets of the trenches would be blown in, and the defensive works destroyed. In this respect, too, the German theory proved correct, and when the trench warfare began in real earnest the Allies had to follow the German example. Months passed, however, before their supply of howitzers and high explosive shells was sufficient to enable them to cope with the Germans on equal terms.
