From this time onwards this northern section of the line was quiet save for small readjustments, until the great effort upon November 13, which brought the autumn campaign to a close with the considerable victory of Beaumont Hamel. From the point which the Second Corps had now reached it could command with its guns the Valley of the Ancre to the north of it, including some of those positions which had repulsed our attack upon July 1 and were still in German hands. So completely did we now outflank them from the south that it must have been evident to any student of the map that Haig was sure, sooner or later, to make a strong infantry advance over the ground which was so completely controlled by his artillery. It was the German appreciation of this fact which had caused their desperate efforts at successive lines of defence to hold us back from gaining complete command of the crest of the slope. It will be told in the final chapter of this volume how this command was utilised, and a bold step was taken towards rolling up the German positions from the south--a step which was so successful that it was in all probability the immediate cause of that general retirement of the whole German front which was the first great event in the campaign of 1917. {281} CHAPTER XII THE BATTLE OF THE SOMME From September 15 to the Battle of the Ancre Capture of Eaucourt--Varying character of German resistance--Hard trench fighting along the line--Dreadful climatic conditions--The meteorological trenches--Hazy Trench--Zenith Trench--General observations--General von Arnim's report. Having described the Battle of Flers, which began upon September 15 and which extended over one, two, or three days according to the completeness of the local victory, or the difficulty of reaching any definite limit, we will now turn once more to the left of the line (always excepting Gough's flanking army, which has been treated elsewhere), and we shall follow the deeds of the successive divisions in each sector up to the end of the operations. We will begin with the Third Corps, who abutted upon the Canadians in the Martinpuich sector, and covered the line up to Drop Alley, north-east of High Wood, where they joined up with the Fifteenth Corps.