Now and then, in perfect German, he whispered a question.  Always he received a reply.  And stowed it away in his tenacious memory for those it most concerned.

At daylight he was asleep by Sara Lee’s kitchen fire.  And at daylight Sara Lee was awakened by much firing, and putting on a dressing gown she went out to see what was happening.  Rene was in the street looking toward the poplar trees.

“An attack,” he said briefly.

“You mean—­the Germans?”

“Yes, mademoiselle.”

She went back into the little ruined house, heavy-hearted.  She knew now what it meant, an attack.  That night there would be ambulances in the street, and word would come up that certain men were gone—­would never seek warmth and shelter in her kitchen or beg like children for a second bowl of soup.

On the kitchen floor by the dying fire Henri lay asleep.

XIII

Much has been said of the work of spies—­said and written.  Here is a woman in Paris sending forbidden messages on a marked coin.  Men are tapped on the shoulder by a civil gentleman in a sack suit, and walk away with him, never to be seen again.

But of one sort of spy nothing has been written and but little is known.  Yet by him are battles won or lost.  On the intelligence he brings attacks are prepared for and counter-attacks launched.  It is not always the airman, in these days of camouflage, who brings word of ammunition trains or of new batteries.

In the early days of the war the work of the secret service at the Front was of the gravest importance.  There were fewer air machines, and observation from the air was a new science.  Also trench systems were incomplete.  Between them, known to a few, were breaks of solid land, guarded from behind.  To one who knew, it was possible, though dangerous beyond words, to cross the inundated country that lay between the Belgian Front and the German lines, and even with good luck to go farther.

Henri, for instance, on that night before had left the advanced trench at the railway line, had crawled through the Belgian barbed wire, and had advanced, standing motionless as each star shell burst overhead, and then moving on quickly.  The inundation was his greatest difficulty.  Shallow in most places, it was full of hidden wire and crisscrossed with irrigation ditches.  Once he stumbled into one, but he got out by swimming.  Had he been laden with a rifle and equipment it might have been difficult.

He swore to himself as his feet touched ground again.  For a star shell was hanging overhead, and his efforts had sent wide and ever increasingly widening circles over the placid surface of the lagoon.  Let them lap to the German outposts and he was lost.

Henri’s method was peculiar to himself.  Where there was dry terrain he did as did the others, crouched and crept.  But here in the salt marshes, where the sea had been called to Belgium’s aid, he had evolved a system of moving, neck deep in water, stopping under the white night lights, advancing in the darkness.  There was no shelter.  The country was flat as a hearth.