It is easy to understand why the submersible did not take a vital part in any of the major naval actions. In the naval battle of to-day we have a number of very high-speed armored craft fighting against one another over ranges extending up to 17,000 yards. There is a constant evolution in the position of the ships which it is impossible to follow from the low point of vantage of a periscope, for the different formations of ships mean nothing to the submersible commander. He is so placed that his range of vision is extremely limited, and, on account of the low speed of his boat while submerged, he can operate over only a very limited area of water while the other vessels are moving many miles. Then, too, he is extremely vulnerable to the effect of enemy shells and to the ramming of enemy ships. Under these conditions the submersible commander is more or less forced to a policy of lying ambushed to surprise his enemy. It is said that the "Lusitania" was decoyed into a nest of submersibles. There was but little chance of torpedoing her in any other way. There is also the statement that Admiral Beatty passed with his battle-cruisers through a flotilla of enemy submersibles without being touched.
Submersibles cannot attack their target in definite formations as do surface vessels, and therefore they cannot operate in numbers with the same effectiveness as do the latter. They must maneuver more or less singly, and at random. Being limited to the torpedo, which, when they are submerged, is their sole weapon of attack, they have an uncertain means of striking their armed enemy. The eccentricities of the automobile torpedo are well known; but, even eliminating the fact that this missile is unreliable, the important question of accuracy in the estimate of range and speed which the submersible commander has to make before firing the torpedo must be considered. There is usually a large percentage of error in his calculations unless the submersible is extremely close to its target. Realizing these limitations, the German submersibles are equipped with small torpedoes, which are generally fired at ranges not exceeding eight hundred to two thousand yards. The necessity of approaching the target so closely is, of course, a tremendous handicap in the general operation of these boats. In view of these facts, it is not surprising that the submersible should not have been able to sweep the capital ship from the seas, as was predicted by certain experts before the war.