The mines were laid in a series of thirteen expeditions, or "excursions," as our men somewhat cheerfully called them. The ten mine-layers participated in each "excursion," all ten together laying about 5,400 mines at every trip. Each trip to the field of action was practically a duplicate of the others; a description of one will, therefore, serve for all. After days, and sometimes after weeks of preparation the squadron, usually on a dark and misty night, showing no lights or signals, would weigh anchor, slip by the rocky palisades of Moray Firth, and stealthily creep out to sea. As the ships passed through the nets and other obstructions and reached open waters, the speed increased, the gunners took their stations at their batteries, and suddenly from a dark horizon came a glow of low, rapidly moving vessels; these were the British destroyers from the Grand Fleet which had been sent to escort the expedition and protect it from submarines. The absolute silence of the whole proceeding was impressive; not one of the destroyers showed a signal or a light; not one of the mine-layers gave the slightest sign of recognition; all these details had been arranged in advance, and everything now worked with complete precision. The swishing of the water on the sides and the slow churning of the propellers were the only sounds that could possibly betray the ships to their hidden enemies. After the ships had steamed a few more miles the dawn began to break; and now a still more inspiring sight met our men. A squadron of battleships, with scout cruisers and destroyers, suddenly appeared over the horizon. This fine force likewise swept on, apparently paying not the slightest attention to our vessels. They steamed steadily southward, and in an hour or so had entirely disappeared. The observer would hardly have guessed that this squadron from Admiral Beatty's fleet at Scapa Flow had anything to do with the American and British mine-layers. Its business, however, was to establish a wall of steel and shotted guns between these forces and the German battle fleet at Kiel. At one time it was believed that the mine forces on the northern barrage would prove a tempting bait to the German dreadnoughts; and that, indeed, it might induce the enemy to risk a second general engagement on the high seas. At any rate, a fleet of converted excursion steamers, laying mines in the North Sea, could hardly be left exposed to the attacks of German raiders; our men had the satisfaction of knowing that while engaged in their engrossing if unenviable task a squadron of British or American battleships—for Admiral Rodman's forces took their regular turn in acting as a "screen" in these excursions—was standing a considerable distance to the south, prepared to make things lively for any German surface vessels which attempted to interfere with the operation.
Now in the open seas the ten mine-layers formed in two columns, abreast of each other and five hundred yards apart, and started for the waters of the barrage. Twelve destroyers surrounded them, on the lookout for submarines, for the ships were now in the track of the U-boats bound for their hunting ground or returning to their home ports. At a flash from the flagship all slackened speed, and put out their paravanes—those under-water outrigger affairs which protected the ships from mines; for it was not at all unlikely that the Germans would place some of their own mines in this field, for the benefit of the barrage builders. This operation took only a few minutes; then another flash, and the squadron again increased its speed. It steamed the distance across the North Sea to Udsire Light, then turned west again and headed for that mathematical spot on the ocean which was known as the "start point"—the place, that is, where the mine-laying was to begin. In carrying out all these manœuvres—sighting the light on the Norwegian coast—the commander was thinking, not only of the present, but of the future; for the time would come, after the war had ended, when it would be necessary to remove all these mines, and it was therefore wise to "fix" them as accurately as possible in reference to landmarks, so as to know where to look for them. All this time the men were at their stations, examining the mines to see that everything was ready, testing the laying mechanisms, and mentally rehearsing their duties. At about four o'clock an important signal came from the flagship:
"Have everything ready, for the squadron will reach 'start point' in an hour and mine-laying will begin."
Up to this time the ships were sailing in two columns; when they came within seven miles of "start point," another signal was broken out; the ships all wheeled like a company of soldiers, each turning sharply to the right, so that in a few minutes, instead of two columns, we had eight ships in line abreast, with the remaining two, also in line abreast, sailing ahead of them. This splendid array, keeping perfect position, approached the starting point like a line of racehorses passing under the wire. Not a ship was off this line by so much as a quarter length; the whole atmosphere was one of eagerness; the officers all had their eyes fixed upon the stern of the flagship, for the glimpse of the red flag which would be the signal to begin. Suddenly the flag was hauled down, indicating:
"First mine over."
If you had been following one of these ships, you would probably have been surprised at the apparent simplicity of the task. The vessel was going at its full speed; at intervals of a few seconds a huge black object, about five feet high, would be observed gliding toward the stern; at this point it would pause for a second or two, as though suspended in air; it would then give a mighty lurch, fall head first into the water, sending up a great splash, and then sink beneath the waves. By the time the disturbance was over the ship would have advanced a considerable distance; then, in a few seconds, another black object would roll toward the stern, make a similar plunge, and disappear. You might have followed the same ship for two or three hours, watching these mines fall overboard at intervals of about fifteen seconds. There were four planters, each of which could and did on several trips lay about 860 mines in three hours and thirty-five minutes, in a single line about forty-four miles long. These were the Canandaigua, the Canonicus, the Housatonic, and the Roanoke. Occasionally the monotony of this procedure would be enlivened by a terrible explosion, a great geyser of water rising where a mine had only recently disappeared; this meant that the "egg," as the sailors called it, had gone off spontaneously, without the assistance of any external contact; such accidents were part of the game, the records showing that about 4 per cent. of all the mines indulged in such initial premature explosions. For the most part, however, nothing happened to disturb the steady mechanical routine. The mines went over with such regularity that, to an observer, the whole proceeding seemed hardly the work of human agency. Yet every detail had been arranged months before in the United States; the mines fell into the sea in accordance with a time-table which had been prepared in Newport before the vessels started for Scotland. Every man on the ship had a particular duty to perform and each performed it in the way in which he had been schooled under the direction of Captain Belknap.
The spherical mine case, which contains the explosive charge and the mechanism for igniting it, is only a part of the contrivance. While at rest on board the ship this case stands upon a box-like affair, about two feet square, known as the anchor; this anchor sinks to the bottom after launching and it contains an elaborate arrangement for maintaining the mine at any desired depth beneath the surface. The bottom of the "anchor" has four wheels, on which it runs along the little railroad track on the launching deck to the jumping-off place at the stern. All along these railroad tracks the mines were stationed one back of another; as one went overboard, they would all advance a peg, a mine coming up from below on an elevator to fill up the vacant space at the end of the procession. It took a crew of hard-working, begrimed, and sweaty men to keep these mines moving and going over the stern at the regularly appointed intervals. After three or four hours had been spent in this way and the ships had started back to their base, the decks would sometimes be covered with the sleeping figures of these exhausted men. It would be impossible to speak too appreciatively of the spirit they displayed; in the whole summer there was not a single mishap of any importance. The men all felt that they were engaged in a task which had never been accomplished before, and their exhilaration increased with almost every mine that was laid. "Nails in the coffin of the Kaiser," the men called these grim instruments of vengeance.
IV
I have described one of these thirteen summer excursions, and the description given could be applied to all the rest. Once or twice the periscope of a submarine was sighted—without any disastrous results—but in the main this business of mine-laying was uneventful. Just what was accomplished the chart makes clear. In the summer and autumn months of 1918 the American forces laid 56,571 mines and the British 13,546. The operation was to have been a continuous one; had the war gone on for two years we should probably have laid several hundred thousand; Admiral Strauss's forces kept at the thing steadily up to the time of the armistice; they had become so expert and the barrage was producing such excellent results that we had plans nearly completed for building another at the Strait of Otranto, which would have completely closed the Adriatic Sea. Besides this undertaking the American mine-layer Baltimore laid a mine-field in the North Irish Channel, the narrow waters which separate Scotland and Ireland; two German submarines which soon afterward attempted this passage were blown to pieces, and after this the mine-field was given a wide berth.
Just what the North Sea barrage accomplished, in the actual destruction of submarines, will never be definitely known. We have information that four certainly were destroyed, and in all probability six and possibly eight; yet these results doubtless measure only a small part of the German losses. In the majority of cases the Germans had little or no evidence of sunken submarines. The destroyers, subchasers, and other patrol boats were usually able to obtain some evidences of injury inflicted; they could often see their quarry, or the disturbances which it made on the surface; they could pursue and attack it, and the resultant oil patches, wreckage, and German prisoners—and sometimes the recovered submarine itself or its location on the bottom—would tell the story either of damage or destruction. But the disconcerting thing about the North Sea barrage, from the viewpoint of the Germans, was that it could do its work so secretly that no one, friend or enemy, would necessarily know a thing about it. A German submarine simply left its home port; attempting to cross the barrage, perhaps at night, it would strike one of these mines, or its antenna; an explosion would crumple it up like so much paper; with its crew it would sink to the bottom; and not a soul, perhaps not even the crew itself, would ever know what had happened to it. It would in truth be a case of "sinking without a trace"—though an entirely legitimate one under the rules of warfare. The German records disclosed anywhere from forty to fifty submarines sunk which did not appear in the records of the Allies; how these were destroyed not a soul knows, or ever will know. They simply left their German ports and were never heard of again. That many of them fell victims to mines, and some of them to the mines of our barrage, is an entirely justifiable assumption. That probably even a larger number of U-boats were injured is also true. A German submarine captain, after the surrender at Scapa Flow, said that he personally knew of three submarines, including his own, which had been so badly injured at the barrage that they had been compelled to limp back to their German ports.