The second point, the so-called "delay" involved in the sieges undertaken by the Allies, proves, when it is put forward, an insufficient acquaintance with contemporary conditions. Any fortress with a considerable garrison left behind untaken would have meant the destruction of the Austrian or Prussian communications, and their destruction at a moment when the Austrian and Prussian forces were actually advancing over a desperately hostile country. Moreover, when acting against forces wholly inferior in discipline and organisation, an untaken fortress is a refuge which one must take peculiar pains to destroy. To throw himself into such a refuge will always stand before the commander of those inferior forces as a last resource. It is a refuge which he will certainly avail himself of ultimately, if it is permitted to him. And when he has so availed himself of it, it means the indefinite survival of an armed organisation in the rear of the advancing invaders. We must conclude, if we are to understand this critical campaign which changed the history of the world, that Coburg did perfectly right in laying siege to one fortress after another before he began what every one expected to be the necessarily successful advance on Paris. The French despair, as one town after another surrendered, is an amply sufficient proof of the excellence of his judgment.
We approach the military problem of 1793, therefore, with the following two fields clear before us:—
1. In the north-east an advance on Paris, the way to which is blocked by a quadrilateral of fortresses: Mons, Maubeuge, Condé, and Valenciennes, with the subsidiary stronghold of Lequesnoy in the neighbourhood of the last. Mons has been in Austrian hands since Dumouriez' retreat; Condé is just cut off from Valenciennes by Coburg's advance, but has not fallen; Valenciennes and the neighbouring Lequesnoy are still intact, and so is Maubeuge. All must be reduced before the advance on Paris can begin. Behind these fortresses is a French army incapable as yet of attacking Coburg's command with any hope of success. Such is the position in the last fortnight of April.
2. Meanwhile, on the Rhine the French garrison in Mayence is besieged; Custine, the French commander in that quarter, has fallen back on the French town of Landau, and is drawing up what are known in history as the Lines of Weissembourg. The accompanying sketch map explains their importance. Reposing upon the two obstacles of the river on the right and the mountains on the left, they fulfilled precisely the same functions as a fortress; and those functions we have just described. Until these lines were carried, the whole of Alsace may be regarded as a fortress defended by the mountains and the river on two sides, and by the Lines of Weissembourg on the third.
A reader unacquainted with military history may ask why the obstruction was not drawn upon the line of the Prussian advance on Paris. The answer is that the presence of a force behind fortifications anywhere in the neighbourhood of a line of communication is precisely equivalent to an obstacle lying right upon those lines. For no commander can go forward along the line of his advance and leave a large undestroyed force close to one side of that line, and so situated that it can come out when he has passed and cut off his communications; for it is by communications that an army lives, especially when it is marching in hostile country.
Strategic situation in early summer of 1793. Mayence besieged, Condé and Valenciennes about to be besieged. Conditions of the double advance on Paris.
Custine, therefore, behind his Lines of Weissembourg, and the besieged garrison in Mayence, correspond to the barrier of fortresses on the north-east and delayed the advance of the Prussians under Wurmser and Brunswick from the Rhine, just as Condé, Valenciennes, and Maubeuge prevented the advance of Coburg on the north-east. Such in general was the situation upon the eastern frontier at the end of that month of April, 1793.
FOUR
Let us first follow the development of the northern position. It will be remembered that all Europe was at war against the French. The Austrians had for allies Dutch troops which joined them at this moment, and certain English and Hanoverian troops under the Duke of York who also joined them.
At this moment, when Coburg found himself in increasing strength, a tentative French attack upon him was delivered and failed. Dampierre, who was in command of all this French "Army of the North," was killed, and Custine was sent to replace him. The Army of the North did not, as perhaps it should have done, concentrate into one body to meet Coburg's threatened advance; it was perpetually attempting diversions which were useless because its strength was insufficient. Now it feinted upon the right towards Namur, now along the sea coast on the left; and these diversions failed in their object. Before the end of the month, Coburg, to give himself elbow room, as it were, for the sieges which he was preparing, compelled the main French force to retreat to a position well behind Valenciennes. It was immediately after this success of Coburg's that Custine arrived to take command on the Belgian frontier, his place on the Rhine being taken by Houchard.
Custine was a very able commander, but a most unlucky one. His plan was the right one: to concentrate all the French forces (abandoning the Rhine) and so form an army sufficient to cope with Coburg's. The Government would not meet him in this, and he devoted himself immediately to the reorganisation of the Army of the North alone. The month of June and half of July was taken up in that task.
Meanwhile, the Austrian siege work had begun, and Condé was the first object of its attention. Upon July 10 Condé fell. Meanwhile Custine had been recalled to Paris, and Valenciennes was invested. Custine was succeeded by Kilmaine, a general of Irish extraction, who maintained his position for but a short time, and was unable while he maintained it to do anything. The forces of the Allies continually increased. The number at Coburg's disposal free from the business of besieging Valenciennes was already larger than the force required for that purpose. And yet another fifteen thousand Hessian troops marched in while the issue of that siege was in doubt. This great advantage in numbers permitted him to get rid of the main French force that was still present in front of him, though not seriously annoying him.
This force lay due south-west of Valenciennes, and about a day's march distant. He depended for the capture of it upon his English and Hanoverian Allies under the Duke of York, but that general's march failed. The distance was too much for his troops in the hot summer weather, and the French were able to retreat behind the line of the Scarpe and save their army intact.
The Duke of York's talents have been patriotically exaggerated in many a treatise. He always failed: and this was among the most signal of his failures.
Kilmaine had hardly escaped from York, drawn up his army behind the Scarpe and put it into a position of safety when he in his turn was deprived of the command, and Houchard was taken from the Rhine just as Custine had been, and put at the head of the Army of the North. Before the main French army had taken up this position of safety, Valenciennes had fallen. It fell on the 28th of July, and its fall, inevitable though it was and, as one may say, taken for granted by military opinion, was much the heaviest blow yet delivered. Nothing of importance remained to block the march of the Armies of the Allies, save Maubeuge.
At about the same moment occurred three very important changes in the general military situation, which the reader must note if he is to understand what follows.
The first was the sudden serious internal menace opposed to the Republican Government; the second was the advent of Carnot to power; the third was the English diversion upon Dunquerque.
The serious internal menace which the Government of the Republic had to face was the widespread rebellion which has been dealt with in the earlier part of this