been training his raw troops at Valenciennes in constant small engagements, with the purpose of invading Belgium, now threw himself into the Argonne by a rapid and daring flank march, almost under the eyes of the Prussian advanced guard, and barred the Paris road, summoning Kellermann to his assistance from Metz. The latter moved but slowly, and before he arrived the northern part of the line of defence had been forced. Dumouriez, undaunted, changed front so as to face north, with his right wing on the Argonne and his left stretching towards Chalons, and in this position Kellermann joined him at St Menehould on the 19th of September. Valmy. Brunswick meanwhile had passed the northern defiles and had then swung round to cut off Dumouriez from Chalons. At the moment when the Prussian manoeuvre was nearly completed, Kellermann, commanding in Dumouriez's momentary absence, advanced his left wing and took up a position between St Menehould and Valmy. The result was the world-renowned Cannonade of Valmy (September 20, 1792). Kellermann's infantry, nearly all regulars, stood steady. The French artillery justified its reputation as the best in Europe, and eventually, with no more than a half-hearted infantry attack, the duke broke off the action and retired. This trivial engagement was the turning-point of the campaign and a landmark in the world's history. Ten days later, without firing another shot, the invading army began its retreat. Dumouriez's pursuit was not seriously pressed; he occupied himself chiefly with a series of subtle and curious negotiations which, with the general advance of the French troops, brought about the complete withdrawal of the enemy from the soil of France. Jemappes. Meanwhile, the French forces in the south had driven back the Piedmontese and had conquered Savoy and Nice. Another French success was the daring expedition into Germany made by Custine from Alsace. Custine captured Mainz itself on the 21st of October and penetrated as far as Frankfurt. In the north the Austrian siege of Lille had completely failed, and Dumouriez now resumed his interrupted scheme for the invasion of the Netherlands. His forward movement, made as it was late in the season, surprised the Austrians, and he disposed of enormously superior forces. On the 6th of November he won the first great victory of the war at Jemappes near Mons and, this time advancing boldly, he overran the whole country from Namur to Antwerp within a month. Such was the prelude of what is called the "Great War" in England and the "Epopee" in France. Before going further it is necessary to summarize the special features of the French army--in leadership, discipline, tactics, organization and movement--which made these campaigns the archetype of modern warfare. At the outbreak of the Revolution the French army, like other armies in Europe, was a "voluntary" long-service army, augmented to some extent in war by drafts of militia.