II.—THE BRITISH OFFENSIVE NORTH OF THE SOMME AND
THE FRENCH OFFENSIVE BETWEEN THE OISE AND AISNE.
August 18-29.
The first phase of the Battle of Picardy was ended, but a great new effort, between the Somme and the Scarpe, was being prepared.
Between the Aisne and the Oise, Mangin's Army attacked the plateaux on August 18th, advancing to the Ailette on the 23rd. (Sketch above).
The Attack between the Oise and Aisne
by the Armies of Generals Mangin
and Humbert, August 18-23.
Following up this advance, Humbert's Army continued its offensive vigorously on the 21st, conquered the northern slopes of Le Plémont, crossed the Divette, and occupied Lassigny. (Sketch above).
By their advance, these two armies threatened the right of the German XVIIIth Army, established on the Chaulnes-Roye line.
At the same time, Byng's Army attacked between the Ancre and Croisilles, whilst Rawlinson's left attacked north of the Somme. (Sketch above).
The Attack between the Somme and Scarpe
by Byng and Rawlinson, August 21-29.