We are now in a position to consider how artillery can best engage the various types of target that offer themselves. The gunner's dream, a mass of infantry in the open, is now but seldom seen, and when it is no battery within range can restrain itself from hurling anything it possesses at such a heaven-sent objective. The most suitable method of procedure is to overwhelm it with a cloud of light shrapnel, burst well above and in front of it, so as to produce a hail of bullets beneath which nothing can live. In the case of the attack of a trench, the method usually employed is a preliminary bombardment by light and medium howitzers, with the object of destroying it and its occupants, or at all events rendering it untenable, by dropping high explosive into it; as soon as the infantry commence the assault, the field guns cover the face of the trench with shrapnel to prevent its defenders manning the parapet with their rifles. It has been found that wire entanglements can be most easily and efficiently destroyed by light shrapnel burst just above or if possible amongst them, followed if necessary by a few light high-explosive shells to uproot the standards without forming deep craters that would impede the assaulting infantry. A hostile battery in position under cover is usually engaged with high explosive from guns or howitzers. It is impossible to count upon a direct hit destroying any of the guns composing it, although such lucky shots have occurred. But the detachments may be forced to remain under cover and the battery communications disorganized. Either result will put the battery out of action so long as the fire continues. The real difficulty of such a target is to discover its exact position. Fortified positions such as redoubts and buildings may be destroyed by the high-explosive fire of heavy guns and howitzers; observation posts by guns, as they are usually small, and, speaking generally, it is easier to hit a small mark with a gun than with a howitzer, owing to the former possessing greater accuracy. A somewhat peculiar feature of modern warfare is retaliation, of which the general principle is that if the enemy incommodes one by the use of his artillery, one or more batteries are ordered to fire a given number of rounds into some place where his troops are known to collect, such as a town or large village behind his lines. Guns firing high explosive are most suitable for this, as the point selected for retaliation is usually beyond the range of howitzers. It is often desired, more usually at night, to prevent the enemy from sending reinforcements to his front line. To effect this end, a "barrage" is established, usually by means of howitzers, which draw a curtain of high explosive between the massing-place of the reinforcements and their goal.