"All right. The more I think of it, the better it is not to be on the roads. Here in the fields we're a lot less likely to run into stray parties. And I'd just about as soon meet Germans as allies. If they're retreating and having trouble, they might hold us up as long as the Germans would. They wouldn't believe we really had despatches." For a time they made good, steady progress. The roar of artillery fire in front of them had been resumed, and now it filled the air, proving that they were much closer to the battle. The great waves of sound beat against their ears, making their heads swim at first, but gradually they grew used to it, and could hear other and more trivial sounds--the chirping of night insects and the occasional hooting of owls. "I don't hear the rifle fire," said Henri, after a time. "Only once in a while, that is. Why is that, I wonder? Are the big guns drowning it?" "No. Because if that were the reason, we wouldn't hear it at all. I think they don't do that at night. It's just a case of trying to find the places where the enemy's troops are massed, and keeping up a steady fire of shells to drive them out. Maybe the searchlights help. They've been fighting all day, you know, and even soldiers have to have some rest. They have to eat and sleep or they can't keep up the work." They crossed more than one road, but stuck to the fields, travelling in a straight line as nearly as they could figure their course. When they had decided to join the Boy Scouts, both had studied the stars, since a knowledge of the heavens is one of the most important things about scouting, and they found what they had learned very valuable now. Thus they could keep their bearings, though owing to their desertion of the roads, Henri confessed that he had very little idea of where they were. "Along the roads one has landmarks," he said. "I have gone all through here, over and over again. My father used to drive this way very often in our automobile." "Well, we can't go very far wrong," said Frank, cheerfully. "All we've got to do is to follow the old German maxim, 'March on the cannon thunder!' That was their one rule in 1870, you know and a very good rule it proved too." So they went on. And they still seemed to be a long way from the seat of the heavy artillery firing when a challenge halted them, as they were about to cross a road. "'Alt! 'Oo goes there?" called a cockney voice sharply. "Friends," cried Frank, instantly. "'Alt, friends, while I 'as a look at you," said the sentry. "Call your officer, please. We are carrying despatches," said Frank. "I'll call 'im, all right. My word! You ain't nothin' but kiddies, you ain't! 'Ere! Corporal of the guard! I sye! Corporal of the guard!" He raised his voice in the shout, and a minute or so later a corporal appeared. "Came up to me, sir," said the sentry. "Said as 'ow they wanted me to call the officer of the guard. Carryin' despatches, they sye they is."