CHAPTER VIII.
THE DOVER PATROL AND THE HARWICH FORCES Vice-Admiral Sir Reginald Bacon has given ("The Dover Patrol, 1915-1917," Hutchinson & Co., 1919.) a most valuable record of the varied work carried out in the Straits of Dover and on the Belgian coast during the period of his command.

There is little to be added to this great record, but it may be of interest to mention the general Admiralty policy which governed the Naval operations in southern waters during the year 1917, and the methods by which that policy was carried out.
The policy which was adopted in southern waters, and especially in the Straits of Dover, was that, so far as the means at our disposal admitted, the Straits should be rendered impassable for enemy ships of all kinds, from battleships to submarines, with a view to protecting the cross-Channel communications of our Army in France, of affording protection to trade in the Channel, and preventing a military landing by the Germans either in the south of England or on the left flank of the Allied Army in France.

So long as the Belgian coast ports remained in German possession, the Naval force that could be based there constituted a very serious menace to the cross-Channel traffic.

This really applied more to destroyers than to submarines, and for this reason: submarines have an infinitely larger radius of action than destroyers, and if the Belgian coast ports had not been in German occupation, the additional 210 miles from the Ems would not have been a matter of serious moment to them, and if sighted on the longer passage they could submerge.

The case was quite different with destroyers or other surface vessels; in the first place they were open to attack by our vessels during the passage to and from the Ems, and in the second the additional distance to be traversed was a matter for consideration, since they carried only limited supplies of fuel.
A fact to which the Admiralty frequently directed attention was that, although annoyance and even serious inconvenience might be caused to the enemy by sea and air operations against Ostend and Zeebrugge, no _permanent_ result could be achieved by the Navy alone unless backed up by an advance on land.