Then and there I had a lesson in the new warfare. Bombardment of the country behind the enemy's trenches is not necessarily to destroy towns. Its strategical purpose, I was told, is to cut off communications, to prevent, if possible, the bringing up of reserve troops and transport wagons, to destroy ammunition trains. I was new to war, with everything to learn. This perfectly practical explanation had not occurred to me. "But how do they know when an ammunition train is coming?" I asked. "There are different methods. Spies, of course, always. And aëroplanes also." "But an ammunition train moves." It was necessary then to explain the various methods by which aëroplanes signal, giving ranges and locations. I have seen since that time the charts carried by aviators and airship crews, in which every hedge, every ditch, every small detail of the landscape is carefully marked. In the maps I have seen the region is divided into lettered squares, each square made up of four small squares, numbered. Thus B 3 means the third block of the B division, and so on. By wireless or in other ways the message is sent to the batteries, and B 3, along which an ammunition train is moving, suddenly finds itself under fire. Thus ended the second lesson! An ammunition train, having safely escaped B 3 and all the other terrors that are spread for such as it, rumbled by, going through the Square. The very vibration of its wheels as they rattled along the street set parts of the old building to shaking. Stones fell. It was not safe to stand near the belfry. Up to this time I had found a certain philosophy among the French and Belgian officers as to the destruction of their towns. Not of Louvain, of course, or those earlier towns destroyed during the German invasion, but of the bombardment which is taking place now along the battle line. But here I encountered furious resentment. There is nothing whatever left of the city for several blocks in each direction round the Cloth Hall. At the time it was destroyed the army of the Allies was five miles in advance of the town. The shells went over their heads for days, weeks. So accurate is modern gunnery that given a chart of a city the gunner can drop a shell within a few yards of any desired spot. The Germans had a chart of Ypres. They might have saved the Cloth Hall, as they did save the Cathedral at Antwerp. But they were furious with thwarted ambition--the onward drive had been checked. Instead of attempting to save the Cloth Hall they focussed all their fire on it. There was nothing to gain by this wanton destruction.