Meanwhile , the Pioneers began work on a new defensive line from Le Mesnil to Athies .
But the trenches on the Green Line had barely been started , and the retreating British troops were streaming through the positions to the rear .
The Pioneers began work on a new defensive line from Le Mesnil to Athies .
But the trenches on the Green Line had barely been started , and the retreating British troops were streaming through the positions to the rear .