 The capture of Le Quesnoy was to be achieved through a series of advances , covered by artillery , by the battalions of the Rifle Brigade with some of the battalions of 1st Infantry Brigade in support . Beginning from the brigade 's existing positions , the first advance was to involve the 1st , 2nd and 4th Rifle Battalions moving forward to a line defining an arc to the west of Le Quesnoy , including the railway line , which was designated the " Blue Line " . Then the 1st Battalion of the 1st Infantry Brigade would push north @-@ east around the town , while the 3rd Rifle Battalion went to the south @-@ east . The advance westwards would culminate in the establishment of a new front line , designated the " Green Line " to the east of Le Quesnoy , which would be manned by the battalions of 1st Brigade . Once the " Green Line " had been formed , the Rifle Brigade was to move into the town , while the battalions of 1st Brigade were to advance further to the west up to the Mormal Forest . 
