The Yankee mining squadron

by Reginald Rowan Belknap

To stop the enemy submarines near their bases, before they could scatter on the trade routes, would obviously defeat their campaign more surely than merely hunting them at large. That was the purpose of the Northern Mine Barrage, which, with the barrage at Dover, made it not impossible but extremely hazardous to enter or leave the North Sea. That many a submarine came to grief in attempting these barriers is now a certainty, and the establishment of the Northern Barrage, which many had thought impossible, insured the early finish of the submarine campaign.

The resumption of ruthless submarine warfare became a serious threat to the cause of the Allies, and at the time of our entry into the war their situation was critical—how much more critical than the world was allowed to know at the time, Admiral Sims has disclosed in his “The Victory at Sea.” The relief brought about through the convoy system, in which our destroyers, the navy’s first participants, had a large share, was immediate and important. But the submarine menace was far from ended and—according to the best information—would soon be greatly augmented, while the increasing number of transports would offer the enemy more opportunities, with the added horror of troopship sinkings in prospect.

Of further measures, the most effective would be such a blockade as would keep the submarines in or from their bases. The British had already mined a large area north and west from Heligoland, but this obstruction was not insurmountable, for the Germans from nearby could always clear a passage through when wanted. In any case, until the Skagerrack passage were closed, the submarines might use that route without hindrance. Two weighty reasons kept the Skagerrack open—unwillingness to violate neutral waters, and the ease with which German forces could raid any barrier near their bases. It may be recalled with what sudden damage a small German cruiser detachment raided a convoy just outside the Skagerrack, in October, 1917.

To be effective, therefore, any barrier must be beyond easy reach of a raiding force and cover the Skagerrack, and must also be far enough to the northward of the British bases not to hamper the battle fleet’s engaging with the enemy. Hence, the anti-submarine barriers should be, one near Dover Strait, the other across the North Sea, from Scotland to Norway.

The closing of Dover Strait, undertaken by the British Navy alone, needs no further mention here. Although the strong tidal currents there, frequent rough seas, and hard, smooth bottom were unfavorable for minefields, other means—such as a line of guard vessels moored not far apart and equipped with powerful searchlights, together with numerous active patrollers—were employed with a considerable degree of success.

The Northern Barrage would be too long a front, and much of it too far from base, for effective patrol without a great number of vessels. A wide, thickly sown minefield, however, would watch night and day in all weathers without relief, and would be even more effective against passage submerged than against passage on the surface, because of the less wear and disturbance of the mines by wave action, deep down under water.

Currents were not strong in the northern location, but the bottom lay as deep as 900 feet, whereas 300 feet had heretofore been the deepest water ever mined. Merely to provide the mines meant a large undertaking, besides involving an enormous quantity of the same high explosive which was likewise in heavy demand for shells and bombs. Supposing the mines ready, the planting of so many would be a long and dangerous operation, employing all the Allies’ existing minelayers indefinitely. And neither the British nor ourselves yet had a mine that was quite satisfactory for the prospective requirements.

Our Naval Bureau of Ordnance, however, was intent on finding the means for such a barrier, so that when, in May, 1917, among the many contrivances offered for winning the war, Mr. Ralph E. Browne, an electrical engineer of Salem, Massachusetts, presented his submarine gun for consideration, Commander S. P. Fullinwider, U.S.N., in charge of the Bureau’s mining affairs, saw that, although the invention was not suitable for naval purposes in the form offered, a new electrical device which it contained, if applied to the firing mechanism of a submarine mine, would result in just what we were looking for—a mine at once sensitive and far reaching. Mr. Browne collaborated with the Bureau of Ordnance in developing the new mine-firing device. By July, 1917, all doubt as to its practicability had been dispelled and the Bureau of Ordnance was able to give assurance that, in urging the closing of the German bases, our navy might offer the means.

Extravagant claims were common in the field of mining inventions, and three years of war lessons in the perversity of mines made the British naturally skeptical of this American find. An experienced officer in mining was sent over to see, Lieutenant R. H. DeSalis, R.N., who had received the D.S.O. for some minelaying on the Belgian coast. As the new device was put through its paces before him, the chill thawed out and in two hours he had become almost an enthusiast. Upon his report the British Admiralty took up the plan with active interest.