At the end of an hour's steady riding, the lads found themselves at the junction of two forked roads, where, contrary to the usual custom, there was no signpost to indicate the direction. On either side was a steep bank. "Now, which way?" asked Rollo. "Neither of the roads looks particularly inviting." "It's one of the sunken roads of Belgium, I suppose," said Kenneth. "We'll climb up this bank. Perhaps we shall be able to see where we are. It will be awkward for our bikes if a motor-car comes tearing along." The incline was nearly fifteen feet in height and fairly steep. When the lads reached the summit they found, to their surprise, that they were on a slightly undulating grass field liberally guarded with barbed wire. About four hundred yards off was a rounded hillock. Even as the two looked they saw a huge cylindrical turret, from which projected the muzzle of a large gun, rise from the ground. For a few seconds the giant weapon moved horizontally and vertically, as if seeking a target, then as swiftly as it had appeared it disappeared into the ground. "I say, we've stumbled across one of the frontier forts," exclaimed Kenneth. "Let's go a bit closer and have a look. I'd like to find out how they work." "Thanks, I'm not having any," objected Rollo. "There's too much barbed wire knocking about. Besides, there are our bikes." "We needn't wriggle under the wire, this road on our right evidently leads to the fort. We'll get a bit closer; but hold on a minute, we'll see if that gun pops up again." They waited for at least five minutes, but without the expected result. As they turned to retrace their steps, they were confronted by a tall Belgian soldier wearing the blue uniform of the artillery. "C'est défendu: marchez!" he ordered sternly. "All right, monsieur," replied Kenneth. "We've lost our way. Which is the Liége road?" "You are foreigners," exclaimed the soldier, bringing his bayonet to the "ready". "Yes, English." "You must come with me." "We have motor-bicycles." "No matter. They will be attended to. Forward!" Realizing the uselessness of attempting to argue the point the lads obeyed, the soldier following three paces in the rear with his rifle and bayonet at the slope. After covering a distance of about a hundred yards between the edge of the barbed-wire entanglements and the dip formed by the sunken road, the arrested lads found themselves in the presence of a corporal and a file of men. "You must be taken before the major. I am sorry, but these are my orders," declared the corporal civilly, after ascertaining that the two chums were English. "No doubt you will be permitted to go with but little delay." "Will our motor-bicycles be all right?" asked Rollo anxiously. "We left them a little way down the lane."