The executive council, directed, as to military operations by general Servan, advanced the newly-levied battalions towards the frontier. As a man of judgment, he was desirous of placing a general at the threatened point; but the choice was difficult. Among the generals who had declared in favour of the late political events, Kellermann seemed only adapted for a subordinate command, and the authorities had therefore merely placed him in the room of the vacillative and incompetent Luckner. Custine was but little skilled in his art; he was fit for any dashing coup de main, but not for the conduct of a great army intrusted with the destiny of France. The same military inferiority was chargeable upon Biron, Labourdonnaie, and the rest, who were therefore left at their old stations, with the corps under their command. Dumouriez alone remained, against whom the Girondists still retained some rancour, and in whom they, moreover, suspected the ambitious views, the tastes, and character of an adventurer, while they rendered justice to his superior talents. However, as he was the only general equal to so important a position, the executive council gave him the command of the army of the Moselle.
Dumouriez repaired in all haste from the camp at Maulde to that of Sedan. He assembled a council of war, in which the general opinion was in favour of retiring towards Chalons or Rheims, and covering themselves with the Marne. Far from adopting this dangerous plan, which would have discouraged the troops, given up Lorraine, Trois Eveches, and a part of Champagne, and thrown open the road to Paris, Dumouriez conceived a project full of genius. He saw that it was necessary, by a daring march, to advance on the forest of Argonne, where he might infallibly stop the enemy. This forest had four issues; that of the Chene-Populeux on the left; those of the Croix-au-Bois and of Grandpre in the centre, and that of Les Islettes on the right, which opened or closed the passage into France. The Prussians were only six leagues from the forest, and Dumouriez had twelve to pass over, and his design of occupying it to conceal, if he hoped for success. He executed his project skilfully and boldly. General Dillon, advancing on the Islettes, took possession of them with seven thousand men; he himself reached Grandpre, and there established a camp of thirteen thousand men. The Croix-au-Bois, and the Chene-Populeux were in like manner occupied and defended by some troops. It was here that he wrote to the minister of war, Servan: - "Verdun is taken; I await the Prussians. The camps of Grandpre and Les Islettes are the Thermopylae of France; but I shall be more fortunate than Leonidas."
In this position, Dumouriez might have stopped the enemy, and himself have securely awaited the succours which were on their road to him from every part of France. The various battalions of volunteers repaired to the camps in the interior, whence they were despatched to his army, as soon as they were at all in a state of discipline. Beurnonville, who was on the Flemish frontier, had received orders to advance with nine thousand men, and to be at Rhetel, on Dumouriez's left, by the 13th of September. Duval was also on the 7th to march with seven thousand men to the Chene-Populeux; and Kellermann was advancing from Metz, on his right, with a reinforcement of twenty-two thousand men. Time, therefore, was all that was necessary.
The duke of Brunswick, after taking Verdun, passed the Meuse in three columns. General Clairfait was operating on his right, and prince Hohenlohe on his left. Renouncing all hope of driving Dumouriez from his position by attacking him in front, he tried to turn him. Dumouriez had been so imprudent as to place nearly his whole force at Grandpre and the Islettes, and to put only a small corps at Chene-Populeux and Coix-au- Bois - posts, it is true, of minor importance. The Prussians, accordingly, seized upon these, and were on the point of turning him in his camp at Grandpre, and of thus compelling him to lay down his arms. After this grand blunder, which neutralized his first manoeuvres, he did not despair of his situation. He broke up his camp secretly during the night of the 14th September, passed the Aisne, the approach to which might have been closed to him, made a retreat as able as his advance on the Argonne had been, and concentrated his forces in the camp at Sainte-Menehould. He had already delayed the advance of the Prussians at Argonne. The season, as it advanced, became bad. He had now only to maintain his post till the arrival of Kellermann and Beurnonville, and the success of the campaign would be certain. The troops had become disciplined and inured, and the army amounted to about seventy thousand men, after the arrival of Beurnonville and Kellermann, which took place on the 17th.