 In the second half of 1916, the British constructed strong defensive underground positions and from August 1916, the Royal Engineers developed a mining scheme for a big infantry attack on the Vimy Ridge proposed for autumn 1916, although this was postponed.After September 1916, when the Royal Engineers had completed their network of defensive galleries along most of the front line, offensive mining largely ceased although activities continued until 1917.The British gallery network beneath Vimy Ridge eventually grew to a length of .