The Russians had already prepared positions on the river line, and by 19th February they had occupied them, and were waiting for the Germans to attack. Next day the enemy launched forces against the Niemen, about fourteen miles to the north of Grodno. A thick belt of wood on the banks of the river screened them from view, and some of them succeeded in crossing the river, but could not emerge from the forests on the other side. Though the railway was less than ten miles away, they were unable to reach it. Meanwhile the fortress of Ossowietz, on the Bobr, was undergoing a second siege. You will remember that the Germans had tried to capture it in the previous September, but had failed, because the fortress stands amidst marshes, and they could not find solid ground from which to fire their big guns. Again they failed, though they used every possible device to bring about its downfall. Every knuckle of hard soil on which a howitzer could be placed was known to the garrison, and they were able to silence the big guns of the enemy before they could do much mischief. It is said that the Germans lost 15,000 dead in their attempts to storm the fortress. Thus the attacks on the Niemen and the Bobr had come to nothing. By the beginning of March the Russians were advancing everywhere along the line from Kovno to the Narev, and the Germans were slowly retiring towards East Prussia. There was desperate fighting with the bayonet amidst the marshy woods near Augustovo, where large captures were made of German guns, supplies, and prisoners. By the middle of March the Germans were covering the East Prussian frontier, and were only ten miles within Russian territory. Meanwhile a great battle had been fought and lost on the Narev. * * * * * Look carefully at the map on p. 115; it shows you the country between the East Prussian frontier and the Narev. This river flows in a winding course through a district of marshes and heavy woods, with here and there a few ridges. To the north of the river, and to the east of the town of Przasnysz,[21] which stands midway between the frontier and the Narev, there are some fairly high hills with patches of forest on their sandy slopes. The crossing-places of the Narev are protected by fortified towns, some of which you see marked by a star on the map.