A patrol area of 2,000 square miles per ship is conservative. It assumes the ship flying at no faster than 35 knots, having visibility of five miles in all directions. As a matter of fact, allowing a little more than 40 knots speed--and the airship cruises considerably faster than that--we might say that a modern blimp could patrol an area 10 miles wide and 500 miles long in the 12 hours, or an area of 5,000 square miles. But by criss-crossing back and forth in accordance with a progressive plan, an area of 2,000 square miles could be made reasonably secure--except under extremely adverse conditions of visibility.
Laying these patrol areas down over the map of submarine operations of 1918 it is apparent that such patrols would cover much of the territory where ship sinkings were achieved, cover all of the areas where mines were laid.
With blimps operating from such bases, in addition to the patrols being executed by other naval craft, we might conclude that no submarine could venture within 100 miles of the American coast during daylight hours without considerable risk of detection, and that blimps should be able to make contribution to the safety of coastwise shipping and harbor cities.
The patrol areas assigned to the blimps would have their flanks exposed, but airship patrol would be co-ordinated with that of airplanes and surface craft, guarding the areas farther out.
That this conclusion is reasonable is indicated by the fact that from 1939 on, Lakehurst Naval Air Station, under command of Commander G. H. Mills had been doing just this, patroling areas all the way from Nantucket to Cape Hatteras.
CHAPTER II British Airships in the First War
Germany entered the first World War with high expectations as to one, perhaps two of its new weapons of war. Its submarines might offset Britain's superiority at sea, and certainly the Zeppelins, which had proved themselves in four years of commercial flying, would be able to cross the English Channel and carry the war to the island which had seen no invasion since William the Conqueror.
No nation except Germany had Zeppelins. And as the German people began to feel the pinch of the blockade, cutting their life line of food and supplies, they brought increasing public pressure on High Command to use these weapons to punish England.