"What's he a-sayin'?" Harry Snowling asked.
"He says: 'How old are you?'" Mark answered. "Tell him ninety-nine," the skipper gravely pursued, giving his ship's number.
Mark spelt out the reply with his flags, knowing that the inquiry and the expected response were merely preliminary. There was a pause; then again the semaphore was worked, and Darby read the message:
You will proceed at once to the position marked Z on your chart, and begin operations, working in parallels from N.E. to S.W. Please repeat.
Mark repeated the message, doing it much quicker then the semaphore had done. The skipper then signalled to his consorts to lift their anchors, and in a very little time the flotilla of mine-sweepers was steaming away between the Forelands and the Goodwins and across the Straits.
The position marked on the chart was to the southward of the British mine-field and off the Belgian coast.
Other trawlers joined in the work of sweeping for explosive mines which were believed to have been laid by the enemy from boats sent out secretly from Zeebrugge and Ostend. For a long time none were found, but as the searchers drew nearer to the Belgian coast one after another was brought up and exploded. On the second day three were exploded by the Dainty and her sweeping partner, the Veronica, and Darby Catchpole realised by experience that mine-sweeping was in actuality a sternly-strenuous, arduous, and exceedingly hazardous calling.
As they worked nearer and nearer to the Belgian coast, ominous sounds came to them across the intervening sea; sounds that told them of the ceaseless warfare on the land. The air was filled with the deep-throated booming of heavy guns, the bursting of high-explosive shells and of shrapnel.
With an almost superhuman effort, the Germans were attempting to make themselves masters of the coast and seaports of Northern France. They had concentrated enormous forces of men and heavy artillery, and were making a tremendous forward movement with the intention of getting round the Allies' left flank and cutting off their communications with England and the Channel.
If, by taking Dunkirk, Calais, and Boulogne, they could command the Straits of Dover, an invasion of Great Britain would, they believed, be simple. They might lay a double field of mines across from shore to shore with a clear way between, through which their crowded transport barges could pass under cover of their batteries of enormous guns.