EASTERN SEA FRONTIER
WAR DIARY
APRIL 1942
  
     
 
CHAPTER VI
  
 
 
 
THE MINE FIELDS
  
     
 
        At the beginning of the war, it will be recalled, the passive defenses of the Frontier, consisting of controlled mine fields, nets and booms, and small contact minefields, were rapidly set in place. These inner defenses of principal harbors and bases were gradually strengthened during the first months of this year, while, at the same time, ambitious plans for the extension of contact mine fields were drawn up. The most impressive of these was a project to form a barrier between Cape Anne and Cape Cod, but this was given up in February in view of the existing shortages of necessary men and equipment.
  
     
          Nevertheless, the subject of mine fields along the coast continued to be debated during this period when the submarine warfare was steadily mounting in intensity. Typical of many proposals was that made in February by the Commander of the Inshore Patrol of the Fifth Naval District. It was his view that "the obviously unsatisfactory anti-submarine measures now possible, due to insufficiency and inadequacy of patrol vessels, and the unsatisfactory results of such offensive action, indicate the necessity of additional steps to combat this menace." The step which he presented for the consideration of higher authority was the laying of deep mine fields in all endangered areas of the coast.  
 
 
          Since that time various plans for mine fields have been under  
     
 
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discussion, but in the past few weeks the debate has concerned itself primarily with two different schemes. A field running down the coast from Hatteras to Canaveral a few miles to seaward of the shipping lanes has been strongly advocated. This, it is felt, would form a protective screen behind which merchant shipping could move with comparative security. It has also been suggested that mine fields be laid at various anchorages along the coast in which shipping could find night refuge. By day vessels would proceed under air coverage along the lanes patrolled by surface craft.
  
     
 
        Both proposals have much to recommend them and each has certain disadvantages. The barrier, in theory, would provide continuous if not complete protection for shipping. Vessels could, therefore, move steadily behind it without breaking their voyages. But these primary advantages would be offset by the following defects. Such an extended screen could always be pierced by intruding submarines. It could increase the hazards of entering the hunting fields, but it could not seal off the shipping lanes from the enemy. It would provide an extra hazard to ships drifting out of control in the event of a breakdown. The great length of the barrier would place a constant burden upon the limited number of vessels available for patrolling mine fields. In general terms the principal disadvantages of this kind of barrier were the high initial expenditure; the continued high rate of upkeep reckoned in terms of men and material; and the impossibility of constructing a field of absolute integrity.
  
     
 
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        Much could be said in favor of the mined anchorage. By setting up six of them along the coast, shipping could be assured of refuge each night of the trip from the Florida Straits to New York. This protection could be afforded at the cost of only 14,000 mines, as opposed to the 30,000 required in the mine barrier. Danger to merchant vessels from the mines was relatively very small and the number of patrol vessels used relatively low. Of particular value was the fact that these anchorages could be made relatively secure against the intruder.
  
     
 
        But there were difficulties as well. The mine fields would have to be laid outside the range of enemy torpedoes--which is about seven miles. This means that in certain areas merchant vessels would have to be diverted from the shipping lanes, that run close inshore, in order to avoid the fields. Likewise a constant patrol of the swept channels will have to be maintained--costly in time and effort. Mined anchorages mean broken voyages which in turn mean slower passage up the coast. Finally, fifty vessels huddled together present a large and attractive target to any submarine bold and fortunate enough to breach the integrity of the field.
  
     
          These relative advantages and disadvantages of the different types of proposed mine fields were analyzed at length in a letter to Opnav written by CESF on April 3rd. In weighing the merits of each he reached the conclusion that the mined anchorage was the more desirable system of defense. Expense in time and money, or difficulties of maintenance are not the most important factors in determining a matter of this sort. The problem resolves itself into a question of which kind of  
 
 
 
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defensive system provides the greatest protection against the submarine. The mined anchorage which, because of its small area, can be more effectively closed against the enemy, when taken together with the patrol and search of shipping lanes obviously provided a greater factor of safety than a continuous though more loosely knit mine barrier. CESF, therefore, recommended that work be undertaken on the construction of mined anchorages below Hatteras. The most important places were Hatteras itself and Cape Fear which were given priority. Throughout the month of April negotiations looking to the establishment of such anchorages were carried forward.
  
     
 
 
     
     
     
     
     
     
     
     
 
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