(See Cover)
On August 25, 1914, seven German Armies totaling 1,700,000 men were spread over a jagged 300-mile front from the Swiss frontier to the outskirts of Paris. In 20 days they had advanced like a vast hinge whose outer point traveled 180 miles, smashed through Belgium, through Mons and down the Oise, occupied 14,000 square miles of France, Belgium and Luxembourg. The French plan of an offensive through the German centre had been abandoned. At Paris, in the headquarters of General Joffre, commanding the French forces, the shock had bereft most officers of any plan except continued retreat.
The original German plan provided that the First Army under Kluck was to pass through Belgium, shoulder the Belgian Army out of the war, march southwest of Paris across the Seine, protecting the German right flank. But in the uncertainty of movement and position, Kluck lost direction, veered toward Paris instead of circling southwest to envelop it. Sensing the significance of the German right wing's undershot, in the evening of August 25, Marshal Joffre's tactical adviser, a smooth, silent, chubby little 42-year-old officer named Maurice Gamelin had written out Joffre's historic Instruction No.2: "Having been unable to carry out the offensive maneuver originally planned, future operations will be conducted in such a way as to reconstruct on our left a force capable to resuming the offensive . . . while the other armies hold the enemy in check for such time as may be necessary."
Kluck continued southeast. Early in the morning of September 4, General Galliéni, military governor of Paris in France's greatest emergency, saw that Kluck was still moving southeast of the city and exposing the German right flank. He rushed his troops into position, telephoned Joffre asking for permission to attack. At six that same morning Colonel Gamelin, inconspicuous in his dark chasseur uniform, mysterious to other officers in his influence on Joffre, saw the same opportunity. He left his lodgings, crossed to Joffre's Operations Section, where officers were arguing over huge military maps scaled at three miles to the inch. He pointed out the opportunity on the map, urged an advance the next day. Joffre came in. Gamelin repeated his opinion. Joffre seemed impressed, discussed it with other officers who were skeptical, postponed decision but wired asking about the condition of the troops who would be called upon to bear the brunt of the offensive. As he was having dinner that night the answers came back. They were moderately encouraging. After dinner Galliéni got Joffre on the telephone, renewed his arguments, and at ten o'clock that night Joffre issued his Instruction No. 6: "It is desirable to take advantage of the exposed position of the German First Army . . . all dispositions will be taken during the day of Sept. 5, with a view of launching an attack on the 6."