The retaking of this city of mine-shafts and pit-heads, electrical power stations, and great hive of mining activity, where a population of something like 40,000 people lived in rows of red-brick cottages, under a forest of high chimneys and mountainous slag-heaps, would cause a thrill through all France, and be one of the greatest achievements of the war--a tremendous feat of arms for the British troops. I looked into the city to-day, down its silent and deserted streets, and I saw a body of our men working forward to get closer to it. They attacked the little wooded hill called the Bois de Riaumont, just to the south of the city, and with great cunning and courage encircled its lower slopes, and made their way into the street of houses behind the line of trees which is the southern way towards Lens. From the western side, up through Liévin, the other troops were advancing cautiously. The enemy was still there in machine-gun redoubts, which will be very troublesome to our men. But they are only rear-guards, for the main body of the enemy has already retreated. When the Canadians swept over the Vimy Ridge, capturing thousands of prisoners, and when yesterday our 24th Division and Canadian troops seized the Bois-en-Hache and the Pimple, two small ridges or knolls below Hill 145, at the northern end of the Vimy Ridge, the enemy saw that his last chance of successful counter-attack was foiled, and at once he was seized with fear and prepared for instant retreat in wild confusion. Lens and Liévin had been stacked with his guns. Both towns had been fortified in a most formidable way, and were strongholds of massed artillery. It is certain that the enemy had at least 150 guns in that great network of mines and pit-heads. But they were all threatened by an advance down the northern slopes of Vimy, and the Canadians were not likely to stay inactive after their great triumph. They were also threatened by the British advance from the Loos battlefields by way of that great pair of black slag-hills called the Double Crassier, famous in this war for close, long, and bloody fighting, where since September of 1915 our men have been only a few yards away from their enemy, and where I saw them last a month or two ago through a chink of wall in a ruined house. German staff officers knew their peril yesterday, and before. From prisoners we know that wild scenes took place in Lens, frantic efforts being made to get away the guns and the stores, to defend the line of retreat by the blowing up of roads, to carry out the orders for complete destruction by firing charges down the mine-shafts, flooding the great mine-galleries so that French property of enormous value should not be left to France, and withdrawing large bodies of troops down the roads under the fire of our long-range guns. Up to dawn yesterday the enemy in Lens hoped that the British pursuit would be held back by the German rear-guards in Vimy and Petit-Vimy villages.