The French Commander-in-Chief was faced by an appalling problem. With forces numbering one-half of those launched against him, he had to await the German attack on a frontier 500 miles long. He was uncertain as to where the main blow would fall. Accordingly he followed Napoleon's advice: "Engage everywhere, and then see." He engaged in Alsace; but the main forces of the enemy were not there. He engaged in Lorraine, and in the third week of August suffered a heavy defeat at the hands of the Bavarians, though he was still able to keep the field in that province. On 23rd August, when the Battle of Nancy was raging, the avalanche fell on the line of the Sambre and Meuse, where French armies were arrayed to meet the shock. Namur, the pivot of the defending armies, fell; its forts were blown to atoms by the great howitzers which unwisely had been permitted to come within range. An unexpected army of Saxons pierced the Allied centre, and the French were forced to retreat rapidly or suffer destruction. The northern gate to Paris was now forced, and the eastern gate in Lorraine was threatened. For a moment it seemed that the Germans had won the campaign in two battles. France had reserves, but they were far away in Alsace, in Burgundy,[3] and behind Paris. They could not be brought to the front in time to retrieve disaster, so the beaten armies had to hasten southwards towards their reserves. The Germans pushed southwards with incredible speed. The British, on the left of the French, had been left unsupported, and overwhelming numbers of the enemy were striving might and main to envelop them. They were in grave peril, and at any moment the right flank in Lorraine might be turned, and the retreating French be caught between two fires. There was nothing for it but swift and desperate retreat, until a line could be reached on which a stand was possible. Here and there, during the rapid retirement, the French gained local successes, which might have tempted them to halt and put their fortune to the test once more. But the French Commander-in-Chief was proof against the temptation. He held firmly to his plan, and continued the long and depressing retreat. [Illustration: A Hand-to-hand Fight during the Battle of the Marne. _By permission of the Sphere._ The action here illustrated took place on the South bank of the Marne, where the Germans found themselves attacked by French colonial troops. The Germans were soon beaten back, after a fierce affray amidst burning houses and broken barricades.]