It has been mentioned that there was an insufficient number of vessels available for use as convoying cruisers. It was estimated that about fifty cruisers or armed merchant ships would be required for this service if the homeward-bound trade to the British Isles alone was considered. An additional twelve vessels would be necessary to deal with the outward-bound trade. At the time only eighteen vessels were available, and these could only be obtained by denuding the North Atlantic entirely of cruisers.
The situation in regard to destroyers or other fast vessels presented equal difficulties. Early in February, 1917, we had available for general convoy or patrol work only fourteen destroyers stationed at Devonport and twelve sloops at Queenstown, and owing to repairs and the necessity of resting officers and men periodically, only a proportion of these were available at any one time. A number of these vessels were required to escort troop transports through the submarine danger zone. During the month of February six sloops were diverted from their proper work of minesweeping in the North Sea and added to the patrol force at Queenstown, and eight destroyers were taken from the Grand Fleet and sent to southern waters for patrol and escort duty. There were obvious objections to this weakening of the North Sea forces, but it was necessary in the circumstances to ignore them.
This total of forty destroyers and sloops represented the whole available force at the end of February. Simultaneously a careful investigation showed that for the institution of a system of convoy and escort for homeward-bound Atlantic trade alone to the United Kingdom, our requirements would be eighty-one destroyers or sloops and forty-eight trawlers (the latter vessels being only suitable for escorting the slow 6-7-knot ships of the trade from Gibraltar to the United Kingdom). For the outward Atlantic trade from the United Kingdom our estimated requirements were forty-four additional destroyers or sloops.
The deficiency in suitable vessels of this class is best shown by the following table, which reveals the destroyer position at different periods during the year 1917:
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Mediterranean.
----------------------------------------------------------------+
Pembroke. |
-------------------------------------------------------------+ |
Queenstown. | |
---------------------------------------------------------+ | |
Bunerana. | | |
------------------------------------------------------+ | | |
North Channel. | | | |
---------------------------------------------------+ | | | |
Scapa and Invergordon. | | | | |
------------------------------------------------+ | | | | |
The Tyne. | | | | | |
---------------------------------------------+ | | | | | |
The Humber. | | | | | | |
------------------------------------------+ | | | | | | |
Lowestoft. | | | | | | | |
---------------------------------------+ | | | | | | | |
The Nore. | | | | | | | | |
------------------------------------+ | | | | | | | | |
Portsmouth. | | | | | | | | | |
---------------------------------+ | | | | | | | | | |
Devonport. | | | | | | | | | | |
------------------------------+ | | | | | | | | | | |
Dover. | | | | | | | | | | | |
---------------------------+ | | | | | | | | | | | |
Harwich Fleet. | | | | | | | | | | | | |
------------------------+ | | | | | | | | | | | | |
Grand Fleet. | | | | | | | | | | | | | |
--------------------+---+--+--+--+--+--+--+--+--+--+--+--+---+--+---
January. | | | | | | | | | | | | | | |
| | | | | | | | | | | | | | |
Flotilla Leaders | 10| 2| 3| | | | | | | | | | | |
| | | | | | | | | | | | | | |
Modern destroyers | 97|45|18|14|13| | | | | | | | | |29
|[A]| | | | | | | | | | | | | |
| | | | | | | | | | | | | | |
Destroyers of River | | | | | | | | | | | | | | |
class and earlier | | | | | | | | | | | | | | |
construction | | |11| 6|16| 9| | 9|11|15| 4| | | | 8
| | | | | | | | | | | | | | |
P boats | | 2| 5| | 4|10| 4| 1| | | | | | |
--------------------+---+--+--+--+--+--+--+--+--+--+--+--+---+--+---
June. | | | | | | | | | | | | | | |
| | | | | | | | | | | | | | |
Flotilla Leaders | 10| 3| 4| | | | | | | | | | | |
| | | | | | | | | | | | | | |
Modern destroyers | 95|23|29|38|15| | | 5| | | | 4| 32| |29
|[A]| | | | | | | | | | | |[B]| |
| | | | | | | | | | | | | | |
Destroyers of River | | | | | | | | | | | | | | |
class and earlier | | | | | | | | | | | | | | |
construction | | |10| 5|16| 7| |29| 1|11| 4| | | | 8
| | | | | | | | | | | | | | |
P boats | | 2| 6| | 8| 9| 4| 1| | | | | | 5|
--------------------+---+--+--+--+--+--+--+--+--+--+--+--+---+--+---
November. | | | | | | | | | | | | | | |
| | | | | | | | | | | | | | |
Flotilla Leaders | 11| 4| 6| | | | | | | | | | | |
| | | | | | | | | | | | | | |
Modern destroyers |101|24|26|37| 9| | | 4| | | |29| 35| |32
|[A]| | | | | | | | | | | |[B]| |
| | | | | | | | | | | | | | |
Destroyers of River | | | | | | | | | | | | | | |
class and earlier | | | | | | | | | | | | | | |
construction | | |10| 4| 8|12| 2|30| |11| 4| | | | 8
| | | | | | | | | | | | | | |
P boats | | 2| 6| |31| | | 1| | | | | |10|
--------------------+---+--+--+--+--+--+--+--+--+--+--+--+---+--+---
[Footnote A: Includes destroyers detached for protection work in other commands.]
[Footnote B: Includes United States destroyers.]
There was the possible alternative of bringing only a small portion of the trade under convoy by taking all the available fast small craft from patrol duty and utilizing them to escort this portion of the trade, but it was felt that as this would leave the whole of the remaining trade entirely without protection, and no fast patrol craft would be on the trade routes to pick up the crews of any merchant ships that might be sunk by submarines, the step was not justified.
The next point for consideration was the possibility of obtaining destroyers or sloops from other sources with which to increase the forces for trade protection. The only commands on which it was possible to draw further were the Grand Fleet, the Harwich and Dover forces, the destroyers of old types working on the East Coast, or the destroyers and "P" boats protecting our cross-Channel communications west of the Dover Command.
It was out of the question to reduce the Harwich or Dover flotillas materially, as we were already running the gravest risks from the inadequacy of these forces to deal with enemy destroyers and submarines operating in southern waters from Zeebrugge or from German ports, and in addition the Harwich Force furnished the sole protection for the weekly convoy running between the Thames and Dutch ports, besides being much required for reconnaissance and offensive operations in the Heligoland Bight so far as it could be spared for this purpose. However, the emergency was such that destroyers were taken from Harwich, as the force obtained new vessels of a faster and more powerful type. The destroyers on the East Coast and in the Portsmouth Command were already inadequate to afford proper protection to the trade and the cross-Channel communications, as evidenced by our losses. Here again, however, in order to meet the very serious situation, some destroyers were eventually transferred to Devonport from Portsmouth, but at the expense of still less protection and fewer opportunities for offensive action against submarines. There remained only the Grand Fleet destroyers on which we could draw yet further. It had always been held that the Grand Fleet required a total force of one hundred destroyers and ten flotilla leaders for the double purpose of screening the ships from submarine attack when at sea and of countering the enemy's destroyers and attacking his heavy ships with torpedo fire in a fleet action. We had gradually built the destroyer force of the Grand Fleet up to this figure by the early spring of 1917, although, of course, it fell far short of requirements in earlier months. It was well known to us that the High Sea Fleet would be accompanied by at least eight flotillas, or eighty-eight destroyers, when proceeding to sea at its selected moment, and it was quite probable that the number might be much higher, as many more vessels were available. At our average moment, even with a nominal force of one hundred destroyers and ten flotilla leaders, we could not expect that more than seventy destroyers and eight leaders would be present with the Fleet, since, in addition to those absent refitting, a considerable number were always engaged on trade protection or anti-submarine work in northern waters which could not join up in time to accompany the Fleet to sea. When the Scandinavian convoy was started in April, 1917, one flotilla leader and six destroyers from the Grand Fleet were used for its protection; other vessels in northern waters also depended on Grand Fleet destroyers for protection. Any further transference, therefore, of destroyers from the Grand Fleet to southern waters for trade protection was a highly dangerous expedient, involving increased risk from submarine attack on the heavy ships in the event of the Fleet proceeding to sea, as well as disadvantages in a Fleet action. The necessity, however, was so great that the risk had to be faced, and for some months of 1917 from eight to twelve Grand Fleet destroyers were used for trade protection in the Atlantic, principally from Irish ports, in addition to those protecting trade in the North Sea.