The mine-sweeping on the enemy minefields was, of course, the principal function of the Harwich auxiliary base. The mined areas that had to be dealt with by this force extended from the south of Lowestoft to the Naze and twenty miles to seawards, while the mine-sweepers of the force were also employed in advance of the Harwich Force on the mined areas on the further side of the North Sea. The Huns had diligently laid their mines in extraordinary numbers in the Harwich area. The German mine-laying submarines did their utmost to block the approaches to Harwich. Captured German mine charts testify to the magnitude of their operations. The Harwich auxiliary force had, therefore, to keep open a swept channel running along the coast, and also several other channels opening from this coast channel eastward, across the minefields, to the swept War-Channel beyond, which served as the highway for merchantmen and other vessels passing up and down the North Sea. It was also part of the duty of the Harwich boats to sweep the War-Channel so far as this channel passes along the Harwich area.
Throughout the war the mine-laying work of the Huns was continuous; that is, so fast as we cleared a channel of their mines, more were laid by their ever-busy submarines. Consequently the work of our mine-sweepers had also to be continuous. The Harwich mine-sweepers' duty was to sweep the above-mentioned channels each day. As light was needed to see and sink the mines after they had been cut adrift, the mine-sweepers used to begin their work at daylight, whatever the conditions of tide or weather, and until they had completed their task no shipping was permitted to proceed up the channels. The risk at low water to the mine-sweepers was therefore very great, and heavy were their losses. They could not await the comparative security of high water, and the preparatory exploratory work of the shallow-draught craft at low water could only be carried out when low water happened to occur at a very early hour, and even then the time available for exploration was very limited. Since the armistice, the mine-sweeping is conducted in far safer conditions. No unnecessary risks are taken; the preliminary exploration at low water can be done thoroughly, and the mine-sweepers can do their part at high water.
For an officer in charge of the War-Channel sweepers the responsibility was very great, and often he had to come to a quick decision when two or more possible courses of action were open to him and it was not easy to foresee which would be the right course, while to take the wrong one would probably mean horrible disaster. I will now give an example of such a situation. In the first place, let it be borne in mind that the conveyance by sea of our foodstuffs, munitions of war, and men was a matter of vital importance to England, and that delays in transportation had to be reduced to a minimum. The Germans, knowing this, for a long time directed all their mine-laying energy to that great highway of shipping, the swept War-Channel extending from the Sunk to the Shipwash light-vessels—the channel the daily sweeping of which was the charge of the Harwich mine-sweepers. Very often, owing to the tides being quite unsuitable for sweepers, the choice had to be made between two evils—stopping all traffic, or risking the sweepers and convoying the traffic through the danger zone.
Now, on the occasion to which I am referring the War-Channel sweepers commenced their work at daylight near the Sunk light-vessel, and sweeping northwards found themselves at 8 a.m., it being dead low water, in the middle of a dangerous freshly laid minefield about half way between the Sunk and the Shipwash lightships, and close to the line of buoys. As some of the mines were showing on the surface, and the others must necessarily have been close underneath, the order was given to stop all traffic. Unfortunately the traffic, and particularly the south-bound portion of it, was very heavy that day, and before all the vessels could be stopped and anchored many of them were in close proximity to the minefield. All, however, were safely anchored, and two hours later, when the flood tide was making, light-draught steamers were set to sweep the area. The job was a difficult one, for the sweepers had to twist and turn among the anchored vessels, and in two cases mines were swept up within fifty feet of these.
In these circumstances it became apparent that the area could not be properly cleared while the merchant vessels lay there at anchor, and some further action was necessary. The officer in charge was faced by a very difficult problem—either he had to keep the whole fleet held up indefinitely, or take the risk of losing one or two of them. In the words of one who told me this story, "If the officer in charge delayed the traffic the powers that be would damn him, and if he lost any of the ships he would be twice damned." So the officer in charge relied upon his lucky star to preserve him from both calamities. Choosing the most favourable time of tide, he ordered all vessels to weigh anchor and steam out of the minefield on a course at right angles to it. Happily all the ships got under weigh safely; the sweepers carried on and swept up eight mines on the ground where the merchantmen had been anchored, thus proving how dangerous had been the situation; and very soon after there were sixty-five vessels in sight steaming north and south along the line of buoys that mark the channel. As my informant said to me, "If anyone spoke of this incident to the officer who gave the order, he would probably shrug his shoulders and say, 'I was lucky'; but he, and he alone, knows what that dreadful hour of anxiety meant to him."
Despite all precautions, many merchant vessels were mined in the War-Channel in the course of the war; but these disasters were largely due to the carelessness of shipmasters, who at times neglected to comply with the instructions that had been given to them. How well the Harwich auxiliary vessels carried out their work, and how heavy that work was, the following figures show. In the year 1917, the total number of enemy mines swept up and destroyed by the mine-sweepers of the thirty-three bases of the British Isles amounted to 3400, of which over 1000 stand to the credit of the Harwich base. It is a notable fact, too, that in the same year 500 mines were destroyed consecutively in this area without the loss of a single merchantman, whereas the average for the United Kingdom had been one merchantman lost to thirteen mines destroyed.