Not only his own liberty, but very probably his own life had depended upon his getting away.

He knew enough, by this time, to understand that the outcome of the first campaign of the war might depend upon the accuracy of the information the Russians obtained of the German movements.
It was plain to Fred that the Russians, in this quarter at least, had not been well served by their spies.

He was surprised at the absence of initiative the Russians had shown in some ways.

Aeroplane scouting, for instance, would have made it impossible for the Germans to spring such a surprise as evidently was in preparation.

The Germans were using their aerial scouts.