The details of the movement were therefore of little moment, and owed the attention they attracted to the habit of measuring progress in war by miles marked on a map. It was the end of January before the preliminary operation of clearing the Beaumont-Hamel spur was completed, and the apparently substantial advance began with the fall of Grandcourt on 7 February. A more ambitious attack on Miraumont from the south of the Ancre was somewhat disconcerted on the 17th by a German bombardment of our troops as they assembled, although the night was dark and misty; for even in France the Germans found spies to work for them, and a number of executions for treachery failed to prevent knowledge of our plans from occasionally reaching the enemy. A week later the German retreat extended, and Warlencourt, Pys, Miraumont, and Serre were evacuated. Again the Germans stopped for a time to breathe, and it was not till 10 March that Irles, a bare mile from Miraumont, was abandoned. By that time the Germans had only rearguards and patrols left either north or south of the Somme, and when on the 17th a general Allied advance was ordered it encountered little resistance. The area of the German withdrawal had spread over a front of a hundred miles from Arras in the north to Soissons in the south. On that day British troops occupied Bapaume, while the French, whose line we had taken over as far as the river Avre, proceeded to liberate scores of villages between it and the Aisne. On that day, too, by one of the apparent illogicalities of French politics, M. Briand's Cabinet, which had held office for the unusual period of eighteen months, resigned.