However, as Americans says, it is “bad business” to dismiss such matters in war with a wave of the hand. I decided to follow the girl. She strolled easily down the road to St. Elois in the twilight. I held off the road behind her as much as I could--wherever the brush would give me footing. The road was nearly if not quite deserted at the time. A few peasants’ carts passed. And I noticed that only one of these peasants apparently knew Marie. They all nodded to her, but they nod to any stranger on the road in that country. But one spoke to her, stopped his horse and they conversed for a minute or more. The talk began with smiles and banter, but presently it seemed to take on a more serious turn. Finally he nodded his head in very decided confirmation of whatever he had told her, started his horse and she resumed her journey to St. Elois. But she no longer strolled. She moved with a smartness of step that kept me going briskly in the concealment of the bushes and trees beside the road to keep up with her. Marie halted before a half-smashed house. The roof was gone and the upper walls, revealing in stark desolation the empty chambers of the upper story. But the ground floor of the house remained intact. Marie loitered for several minutes before this house before she entered it. In fact, she waited until darkness had completely enveloped the place. I stole up to the house and groped around the walls. In the rear, a light popped out of a window. I wasn’t by any means certain that these things meant Marie was a spy. For all I knew she might be a refugee. One found many a refugee Belgian family quartered in such battered places in those days. The fact that some of the peasant carters had apparently not known her could also be laid to the same circumstances--that of her being a peasant girl who had fled from a village in German possession. But simultaneously with the popping up of the light, I heard a sound that swept from my mind all such explanations regarding Marie. It came quite clearly--the cooing of pigeons. That, decidedly, I didn’t like. The carrier-pigeon has played an equal, if not greater, part with any other method of secret communication. Not one of the great powers of the war but has from 100,000 to 125,000 such feathered informants working between their headquarters and stations in the enemy lines established by spies. The wireless, telephones, secret codes, expert signaling of modern warfare has not supplanted the carrier-pigeon.