The British Navy in Battle

by Arthur Joseph Hungerford Pollen

CHAPTER IX
The Destruction of “Koenigsberg”

The story of the destruction of Koenigsberg by the twin monitors Severn and Mersey in the Rufigi Delta, has an interest that far transcends the intrinsic military importance of depriving the enemy of a cruiser already useless in sea war. For the narrative of events will bring to our attention at once the extreme complexity and the diversity of the tasks that the Royal Navy in war is called upon to discharge. It is worth examining in detail, if only to illustrate the novelty of the operations which officers, with no such previous experience, may at any moment be called upon to undertake, and the extraordinary combination of patience, courage, skill, and energy with which when experience at last comes, it is turned to immediate profit. The incident possesses, besides, certain technical aspects of the very highest importance. For it gives in its simplest form perfect examples of how guns should not and should be used when engaged in indirect fire, and by affording this illuminating contrast, is highly suggestive of the progress that may be made in naval gunnery when scientific method is universally applied. The incident, then, is worth setting out and examining in some detail, and there is additional reason for doing this, in that the accounts that originally appeared were either altogether inaccurate or so incomplete as to be misleading. First, then, to a narrative of the event itself.

Koenigsberg was a light unarmoured cruiser of about 3,400 tons displacement, and was laid down in December 1905. She carried an armament of ten 4.1-inch guns, and was protected by a 2-inch armoured deck. The Germans had begun the construction of vessels of this class about seven years before with Gazelle, which was followed in the next year by Niobe and Nymphe, and then by four more—including Ariadne, destroyed by Lion in the affair of the Heligoland Bight—which were laid down in 1900. Two years later came the three Frauenlobs, and the Bremen class—five in number—succeeded these in 1903–4. In 1905 followed Leipzig, Danzig, and finally the ship that concerns us to-day. All these vessels had the same armament, but in the six years the displacement had gone up 1,000 tons. The speed had increased from 21½ knots to about 24, and the nominal radius of action by about 50 per cent. Koenigsberg was succeeded by the Stettins in 1906–7, the two Dresdens in 1907–8, the four Kolbergs in 1908–9, and the four Breslaus in 1911. Karlsruhe, Grodenz, and Rostock were the only three of the 1912–13 programmes which were completed when the war began. The process of growth, illustrated in the advance of Koenigsberg over Niobe, was maintained, so that in the Karlsruhe class in the programme of 1912, while the unit of armament is preserved, we find that the number of guns had grown from ten to twelve; the speed had advanced from 23½ to 28 knots, and the displacement from 3,400 to nearly 5,000 tons. As we know now, in the Battle of Jutland we destroyed light cruisers of a still later class in which, in addition to every other form of defence, the armament had been changed from 4.1-inch to 6.7 guns.

Koenigsberg, on the very eve of the outbreak of war, was seen by three ships of the Cape Squadron off Dar-es-Salaam, the principal port of German East Africa. She was then travelling due north at top speed, and was not seen or heard of again until, a week later, she sank the British steamer City of Winchester near the island of Socotra. There followed three weeks during which no news of her whereabouts reached us. At the end of the month it was known that she had returned south and was in the neighbourhood of Madagascar. At the end of the third week in September she came upon H.M.S. Pegasus off Zanzibar. Pegasus was taken completely unawares while she was cleaning furnaces and boilers and engaged in general repairs. It was not possible then for her to make any effective reply to Koenigsberg’s sudden assault, and a few hours after Koenigsberg left she sank. Some time between the end of September and the end of October, Koenigsberg retreated up one of the mouths of the Rufigi River, and was discovered near the entrance on October 31 by H.M.S. Chatham. From then onwards, all the mouths of the river were blockaded and escape became impossible. Her captain seemingly determined, in these circumstances, to make the ship absolutely safe. He took advantage of the high water tides, and forced his vessel some twelve or more miles up the river. Here she was located by aeroplane at the end of November. Various efforts had been made to reach her by gunfire. It was asserted at one time that H.M.S. Goliath had indeed destroyed her by indirect bombardment. But there was never any foundation for supposing the story to be true, and if in the course of any of these efforts the ship suffered any damage, it became abundantly clear, when she was finally engaged by the monitors, either that her armament had never been touched, or that all injuries had been made good.

The problems which the existence of Koenigsberg propounded were: first, Was it a matter of very urgent moment to destroy her? Second, How could her destruction be effected? The importance of destroying her was great. There was, of course, no fear of her affecting the naval position seriously if she should be able to escape; but that she could do some, and possibly great, damage if at large, the depredations of Emden in the neighbouring Indian Ocean, and of Karlsruhe off Pernambuco, had proved very amply indeed. If she was not destroyed then, a close blockade would have to be rigidly maintained, and it was a question whether the maintenance of the blockade would not involve, in the end, just as much trouble as her destruction. Then there was a further point. Sooner or later, the forces of Great Britain and Belgium would certainly have to undertake the conquest of German East Africa. While Koenigsberg could not be used as a unit for defence, her crew and armament might prove valuable assets to the enemy. Finally, there was a question of prestige. The Germans thought that they had made their ship safe. If the thing was possible, it was our obvious duty to prove that their confidence was misplaced.

If the ship was to be destroyed, what was to be the method of her destruction? She could not be reached by ship’s guns. For no normal warship of superior power would be of less draught than Koenigsberg, and unless the draught were very materially less, it would be quite impossible to get within range, except by processes as slow and laborious as those by which she had attained her anchorage. Was it worth while attempting a cutting-out expedition? It would not, of course, be on the lines of the dashing and gallant adventures so brilliantly drawn for us by Captain Marryat. The boats would proceed under steam and would not be rowed; they would not sally out to board the enemy and fight his crew hand to hand, but to get near enough to start a torpedo at him, discharged from dropping gear in a picket boat. To have attempted this would have been to face a grave risk, for not only might the several entrances be mined, but the boats clearly would have to advance unprotected up a river whose banks were covered with bush impenetrable to the eye. The enemy, it was known, had not only considerable military forces in the colony, but those well supplied with field artillery. And there were on board Koenigsberg not only the 4.1-inch guns of her main armament, but a considerable battery of eight or perhaps twelve, 3-inch guns—a weapon amply large enough to sink a ship’s picket boat, and that with a single shot. An attack by boats then promised no success at all, for the excellent reason that it would be the simplest thing on earth for the enemy to defeat it long before the expedition had reached the point from which it could strike a blow at its prey.

There was then only one possible solution of the problem. It was to employ armed vessels of sufficient gun-power to do the work quickly, and of shallow enough draught to get to a fighting range quickly. If the thing were not done quickly, an attack from the masked banks might be fatal. If the guns of such a vessel were corrected by observers in aeroplanes, they might be enabled to do the trick. Fortunately, at the very opening of the war, the Admiralty had purchased from the builders three river monitors, then under construction in England for the Brazilian Government. They drew but a few feet. Their free board was low, their centre structure afforded but a small mark; the two 6-inch guns they carried fore and aft were protected by steel shields. They had been employed with marked success against the Germans in their first advance to the coast of Belgium. When the enemy, having established himself in the neighbourhood of Nieuport, had time to bring up and emplace long-range guns of large calibre, the further employment of these river monitors on this, their first job, was no longer possible. For the moment, then, they seemed to be out of work, and here was an undertaking exactly suited to their capacity. It was not the sort of undertaking for which they had been designed. But it was one to which, undoubtedly they could be adapted. Of the three monitors Mersey and Severn were therefore sent out to Mafia Island, which lies just off the Rufigi Delta and had been seized by us early in the proceedings.

The first aeroplanes available proved to be unequal to the task, because of the inadequacy of their lifting power. The atmosphere in the tropics is of a totally different buoyancy from that in colder latitudes, and a machine whose engines enable it to mount quite easily to a height of 4,000 or 5,000 feet in Northern Europe, cannot, in Central Africa, rise more than a few hundred feet from the ground. New types of machines, therefore, had to be sent, and these had to be tested and got ready for work. For many weeks then, before the actual attack was undertaken, we must picture to ourselves the Island of Mafia, hitherto unoccupied and indeed untouched by Europeans, in the process of conversion into an effective base for some highly complicated combined operations of aircraft and sea force. The virgin forest had to be cleared away and the ground levelled for an aerodrome. The flying men had to study and master machines of a type of which they had no previous experience. The monitors had to have their guns tested and their structural arrangement altered and strengthened to fit them for their new undertaking. And indeed preparing the monitors was a serious matter. The whole delta of the Rufigi is covered with forest and thick bush—nowhere are the trees less than sixty feet high, and in places they rise to nearly three times this height. To engage the Koenigsberg with any prospect of success, five, six, or seven miles of one of the river branches would certainly have to be traversed. There was, it is true, a choice of three mouths by which these vessels might proceed. But it would be almost certain that the different mouths would be protected by artillery, machine guns, and rifles, and highly probable that one or all of them would be mined. The thick bush would make it impossible for the monitors to engage any hidden opponents with sufficient success to silence their fire. And obviously any portion of the bank might conceal, not only field guns and riflemen, but stations from which torpedoes could be released against them. It was imperative therefore, to protect the monitors from such gun fire as might be encountered, and to take every step possible to preserve their buoyancy if a mine or torpedo was encountered.

The Trent had come out as a mother ship to these two unusual men-of-war, and from the moment of their arrival, she became an active arsenal for the further arming and protection of her charges. Many tons of plating were laid over their vulnerable portions—the steering gear, magazines, navigating bridges, etc., having to be specially considered. The gun shields were increased in size, and every precaution taken to protect the gunners from rifle fire. Where plating could not be added, sandbags were employed. By these means the danger of the ship being incapacitated, or the crew being disabled by what the enemy could do from the bank, was reduced to a minimum. These precautions would not, of course, have been a complete protection against continuous hitting by the plunging fire of Koenigsberg’s artillery. The more difficult job was to protect the ships against mines and torpedoes. Their first and best protection, of course, was their shallow draught. But it was not left at that; and most ingenious devices were employed which would have gone a fair way to keep the ships floating even had an under-water mine been exploded beneath the bottom. At intervals, between these spells of dockyard work, the monitors were taken out for practice in conjunction with the aeroplanes. Mafia Island, which had already served as a dockyard and aerodrome, was now once more to come in useful as a screen between the monitors and the target. The various operations necessary for indirect fire were carefully studied. Gun-layers, of course, cannot aim at a mark they cannot see. The gun, therefore, has to be trained and elevated on information exteriorly obtained, and some object within view—at exactly the same height above the water as the gun-layer—has to be found on which he is to direct his sight. The gun is now elevated to the approximate range, a shot is fired and the direction of the shot and the distance upon the sight are altered in accordance with the correction. At last a point of aim for the gun-layer, and a sight elevation and deflection are found, and his duty then is to fire away, aiming perhaps at a twig or a leaf a few hundred yards off, while the projectile he discharges falls upon a target four, five, or even six miles off.