The Crisis of the Naval War in WW1. John Rushworth Jellicoe
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to merchant ships of guns of sufficient power to prevent the submarine engaging at ranges at which the fire could not be returned. Whilst the method of defence was apparent, the problem of supplying suitable guns in sufficient numbers was a very different matter. It involved arming all our merchant ships with guns of 4-inch calibre and above. In January, 1917, only some 1,400 British ships had been so armed since the outbreak of war.
It will be seen, therefore, that so long as ships sailed singly, very extensive supplies of guns were required to meet gun attack, and as there was most pressing need for the supply of guns for the Army in France, as well as for the anti-aircraft defence of London, the prospect of arming merchant ships adequately was not promising.
When the enemy commenced unrestricted submarine warfare attack by gun-fire was gradually replaced by attack by torpedo, and the problem at once became infinitely more complicated.
Gun-fire was no longer a protection, since the submarine was rarely seen. The first intimation of her presence would be given by the track of a torpedo coming towards the ship, and no defence was then possible beyond an endeavour to manoeuvre the ship clear of the torpedo. Since, however, a torpedo is always some distance ahead of the bubbles which mark its track (the speed of the torpedo exceeding 30 knots an hour), the track is not, as a rule, seen until the torpedo is fairly close to the ship unless the sea is absolutely calm. The chance of a ship of low speed avoiding a hit by a timely alteration of course after the torpedo has been fired is but slight. Further, the only difficulty experienced by a submarine in hitting a moving vessel by torpedo-fire, once she has arrived in a position suitable for attack, lies in estimating correctly the course and speed of the target. In the case of an ordinary cargo ship there is little difficulty in guessing her speed, since it is certain to be between 8 and 12 knots, and her course can be judged with fair accuracy by the angle of her masts and funnel, or by the angle presented by her bridge.
It will be seen, then, how easy was the problem before the German submarine officers, and how very difficult was that set to our Navy and our gallant Mercantile Marine.
It will not be out of place here to describe the methods which were in force at the end of 1916 and during the first part of 1917 for affording protection to merchant shipping approaching our coasts from the direction of the Atlantic Ocean.
The general idea dating from the early months of the war was to disperse trade on passage over wide tracts of ocean, in order to prevent the successful attacks which could be so easily carried out if shipping traversed one particular route. To carry out such a system it was necessary to give each vessel a definite route which she should follow from her port of departure to her port of arrival; unless this course was adopted, successive ships would certainly be found to be following identical, or practically identical, routes, thereby greatly increasing the chance of attack. In the early years of the war masters of ships were given approximate tracks, but when the unrestricted submarine campaign came into being it became necessary to give exact routes.
The necessary orders were issued by officers stationed at various ports at home and abroad who were designated Shipping Intelligence or Reporting Officers. It was, of course, essential to preserve the secrecy of the general principles governing the issue of route orders and of the route orders themselves. For this reason each master was only informed of the orders affecting his own ship, and was directed that such orders should on no account fall into the hands of the enemy.
The route orders were compiled on certain principles, of which a few may be mentioned:
(a) Certain definite positions of latitude and longitude were given through which the ship was required to pass, and the orders were discussed with the master of each vessel in order to ensure that they were fully understood.
(b) Directions were given that certain localities in which submarines were known to operate, such as the approaches to the coast of the United Kingdom, were, if possible, to be crossed at night. It was pointed out that when the speed of the ship did not admit of traversing the whole danger area at night, the portion involving the greatest danger (which was the inshore position) should, as a rule, be crossed during dark hours.
(c) Similarly the orders stated that ships should, as a rule, leave port so as to approach the dangerous area at dusk, and that they should make the coast at about daylight, and should avoid, as far as possible, the practice of making the land at points in general use in peace time.
(d) Orders were definite that ships were to zigzag both by day and at night in certain areas, and if kept waiting outside a port.
(e) Masters were cautioned to hug the coast, as far as navigational facilities admitted, when making coastal passages.
The orders (b), (c) and (d) were those in practice in the Grand Fleet when circumstances permitted during my term in that command.
A typical route order from New York to Liverpool might be as follows:
"After passing Sandy Hook, hug the coast until dark, then make a good offing before daylight and steer to pass through the following positions, viz:
| Lat. 38° N. | Long. 68° W. |
| Lat. 41° N. | Long. 48° W. |
| Lat. 46° N. | Long. 28° W. |
| Lat. 51° 30' N. | Long. 14° W. |
"Thence make the coast near the Skelligs approximately at daylight, hug the Irish coast to the Tuskar, up the Irish coast (inside the banks if possible), and across the Irish Channel during dark hours. Thence hug the coast to your port; zigzag by day and night after passing, Long. 20° W."
Sometimes ships were directed to cross to the English coast from the south of Ireland, and to hug the English coast on their way north.
The traffic to the United Kingdom was so arranged in the early part of 1917 as to approach the coast in four different areas, which were known as Approach A, B, C, and D.
Approach A was used for traffic bound towards the western approach to the English Channel.
Approach B for traffic making for the south of Ireland.
Approach C for traffic making for the north of Ireland.
Approach D for traffic making for the east coast of England via the north of Scotland.
The approach areas in force during one particular period are shown on Chart A (in pocket at the end of the book). They were changed occasionally when suspicion was aroused that their limits were known to the enemy, or as submarine attack in an area became intense.
The approach areas were patrolled at the time, so far as numbers admitted, by patrol craft (trawlers, torpedo-boat destroyers, and sloops), and ships with specially valuable cargoes were given directions to proceed to a certain rendezvous on the outskirts of the area, there to be met by a destroyer or sloop, if one was available for the purpose. The areas were necessarily of considerable length, by reason of the distance from the coast at which submarines operated, and of considerable width, owing to the necessity for a fairly wide dispersion of traffic throughout the area. Consequently, with the comparatively small number of patrol craft available, the protection afforded was but slight, and losses were correspondingly heavy. In the early spring of 1917, Captain H.W. Grant, of the Operations Division at the Admiralty, whose work in the Division was of great value, proposed a change in method by which the traffic should be brought along certain definite "lines" in each approach area. Typical lines are shown in Chart B.
The idea was that the traffic in, say, Approach Route B, should, commencing on a certain date, be ordered by the Routeing Officer to pass along the line Alpha. Traffic would continue along the line for a certain period, which was fixed at five days, when it would be automatically diverted to another line, say Gamma, but the traffic along Gamma would not commence until a period of 24 hours had elapsed since discontinuance of the use of the line Alpha. This was necessary in order to give time for the patrol craft to change from one line to the other. During this period of 24 hours the arrangement for routeing at the ports of departure ensured that