Inspired by this success the Russians pushed forward. But the Germans contested every foot of ground. The Russian movement, too, was considerably hampered by the excellence of the German means of obtaining information. Their airmen were everywhere in evidence, and displayed the greatest courage and daring in face of the Russian aeroplanes, which were mostly of the heavy Sikorski type. The latter, excellent machines though they are, were outmatched in point of speed by the German Taube machines, and were therefore unable to deal effectively with the menace from the air. The country, too, was infested with spies. Every movement of the Russians was signalled to the defending forces. On one occasion a large force of Cossacks was sent to carry out a surprise attack on a German force occupying a village to the south of Stalluponen. As they moved forward, it was noticed that a haystack had caught alight. A tramp and a pipe were the explanation. The owner was greatly upset at his loss and made every effort to save his property. He worked with desperate energy, throwing bucket after bucket of water on the flames. The only result, however, was that a dense column of black smoke rose from the stack. The Cossacks pushed on. A couple of miles from the village they had to pass through wooded country. Suddenly a storm of lead swept through them. They had been ambushed. In close formation, and scarcely able to turn, they were mowed down by the score. When the few survivors returned to their headquarters the haystack was still smouldering, but the owner had disappeared. It was found subsequently that the “water” which he had so vigorously thrown on the flames was a chemical solution which had caused the dense clouds of smoke, serving to warn the Germans of the coming attack. The advance, however, continued in spite of all the courage and cunning displayed by the Germans. The Russian cavalry in particular distinguished itself by its dash and bravery. The German advance guards and outposts were overwhelmed by the fury of its attack. Thanks to its superb, almost reckless, bravery and its bewildering mobility, the way was cleared for the main army, so that on the 19th it found itself facing a strong German army defending Gumbinnen. In the meantime a Russian force had advanced in a north-westerly direction from Bialestock and had crossed the frontier at Prostken. Moving rapidly, it captured Lyck after a sharp engagement, and pushed on towards Lotzen. Here their progress was barred by a German army corps holding a strong position. Some desperate fighting ensued, but the Russians forced their way into the town and the Germans retreated northward along the lakes towards their main army at Gumbinnen.