It was midnight, June 9, 1918. The French forces along the defensive line running in a north-south direction from Montdidier to Compiegne had been braced for two days, following a warning that an attack was imminent. The 62 divisions of the German army under the command of General Ludendorff had been advancing steadily since March 21, which marked the beginning of the German spring offensive. That advance had started with a German victory at the second battle of the Somme.
The German army had attacked a weak point in the British lines between the Oise River and Cambrai with devastating results. Then a second attack, on April 9, had driven a wedge in the lines just north of Soissons.
After a long pause to regroup and supply the front line units, a third attack from the left was launched on May 27 between Soissons and Reims. It pushed the entire front line considerably further to the south. They were now poised to strike Paris, the French capital. In a little over two months, the German forces had rapidly thrust forward along a 100 mile front and were now only 30 miles from Paris, at Chateau-Thiery, in the east and 50 miles, at Montdidier, in the north.
The German forces paused again to consolidate their gains and they prepared for the final thrust. The French command knew that the only chance they had of stopping this advance was by concentrating their outnumbered forces at the exact point of the next German attack. But where would that be?
Page 23 from “SECRET CODE BREAKER II – A Cryptanalyst’s Handbook “