But the war was only a few weeks old when the captain of the U-9, cruising down the Dutch coast, discovered that his gyro compass was off, and when he got his bearings saw that he was 50 miles off course. He wasted no breath, however, on many-syllabled German swear words, for off on his southern horizon were the masts of three British ships. He dived, came up alongside, and in 30 minutes, single handed, with well directed torpedoes, had sunk in turn HMS Aboukir, Hogue and Cressy.
The morning of September 22, 1914, marked the beginning of a new era in Naval warfare. The warring nations grew furiously busy building their own U-boats and devising defenses against the enemy's. Among these defenses was the non-rigid airship.
These two vehicles, so widely different, have much in common. If we may be technical for a minute we may say that the airship and the submarine are both buoyant bodies, completely immersed and floating in a medium--air and water respectively--of changing pressures, that each uses dual sets of steering gear and rudders to control direction and altitude. And further, that the airship in 1941 faces the same division of opinion as the submarine faced in 1914, as to whether, particularly with rigid airships, it will ever be widely used and accepted.
In any event in 1914 there was an urgent and immediate job to be done.
Indicator nets and high explosive mines might give some protection to harbors, might be stretched across steamship lanes and planted around the hiding places of the submarines, if those could be discovered. But troop ships and munition ships and food ships must be dispatched without interruption across the tricky waters of the English Channel to France, and for this purpose convoy escorts were devised, with camouflaged warships zigzagging alongside, while high aloft in lookout stations men with binoculars strained their eyes, searching the waters, ahead, astern, alongside, their search lingering long over every bit of floating wreckage--and there was a lot of it--to make sure it was not a periscope.
These lookouts aboard ship quickly had a new ally in the air. As the submarine menace grew, binoculars began to flash too from the fuselages of bobbing blimps overhead. At a few hundred or perhaps a thousand feet elevation they could see deep below the surface, and quickly learned to recognize at considerable distance the tell-tale trail of bubbles or feathered waters or smear of oil which denoted the enemy's presence, might even pick out the shadowy form of the submerged craft itself.