The scientific duel which was now to take place was likely to task the genius and to bring into full display the peculiar powers and defects of the two chieftains of Europe. Each might be considered to be still in the prime of life, but Alexander, who was turned of forty-five, was already broken in health, while the vigorous Henry was eight years younger, and of an iron constitution. Both had passed then lives in the field, but the king, from nature, education, and the force of circumstances, preferred pitched battles to scientific combinations, while the duke, having studied and practised his art in the great Spanish and Italian schools of warfare, was rather a profound strategist than a professional fighter, although capable of great promptness and intense personal energy when his judgment dictated a battle. Both were born with that invaluable gift which no human being can acquire, authority, and both were adored and willingly obeyed by their soldiers, so long as those soldiers were paid and fed.

The prize now to be contended for was a high one. Alexander's complete success would tear from Henry's grasp the first city of Christendom, now sinking exhausted into his hands, and would place France in the power of the Holy League and at the feet of Philip. Another Ivry would shatter the confederacy, and carry the king in triumph to his capital and his ancestral throne. On the approach of the combined armies under Parma and Mayenne, the king had found himself most reluctantly compelled to suspend the siege of Paris. His army, which consisted of sixteen thousand foot and five thousand horse, was not sufficiently numerous to confront at the same time the relieving force and to continue the operations before the city. So long, however, as he held the towns and bridges on the great rivers, and especially those keys to the Seine and Marne, Corbeil and Lagny, he still controlled the life-blood of the capital, which indeed had almost ceased to flow.

On the 31st August he advanced towards the enemy. Sir Edward Stafford, Queen Elizabeth's ambassador, arrived at St. Denis in the night of the 30th August. At a very early hour next morning he heard a shout under his window, and looking down beheld King Henry at the head of his troops, cheerfully calling out to his English friend as he passed his door. "Welcoming us after his familiar manner," said Stafford, "he desired us, in respect of the battle every hour expected, to come as his friends to see and help him, and not to treat of anything which afore, we meant, seeing the present state to require it, and the enemy so near that we might well have been interrupted in half-an-hour's talk, and necessity constrained the king to be in every corner, where for the most part we follow him."

That day Henry took up his headquarters at the monastery of Chelles, a fortified place within six leagues of Paris, on the right bank of the Marne. His army was drawn up in a wide valley somewhat encumbered with wood and water, extending through a series of beautiful pastures towards two hills of moderate elevation. Lagny, on the left bank of the river, was within less than a league of him on his right hand. On the other side of the hills, hardly out of cannon-shot, was the camp of the allies. Henry, whose natural disposition in this respect needed no prompting, was most eager for a decisive engagement. The circumstances imperatively required it of him. His infantry consisted of Frenchmen, Netherlanders, English, Germans, Scotch; but of his cavalry four thousand were French nobles, serving at their own expense, who came to a battle as to a banquet, but who were capable of riding off almost as rapidly, should the feast be denied them. They were volunteers, bringing with them rations for but a few days, and it could hardly be expected that they would remain as patiently as did Parma's veterans, who, now that their mutiny had been appeased by payment of a portion of their arrearages, had become docile again. All the great chieftains who surrounded Henry, whether Catholic or Protestant—Montpensier, Nevers, Soissons, Conti, the Birons, Lavradin, d'Aumont, Tremouille, Turenne, Chatillon, La Noue—were urgent for the conflict, concerning the expediency of which there could indeed be no doubt, while the king was in raptures at the opportunity of dealing a decisive blow at the confederacy of foreigners and rebels who had so long defied his authority and deprived him of his rights.

Stafford came up with the king, according to his cordial invitation, on the same day, and saw the army all drawn up in battle array. While Henry was "eating a morsel in an old house," Turenne joined him with six or seven hundred horsemen and between four and five thousand infantry. "They were the likeliest footmen," said Stafford, "the best countenanced, the best furnished that ever I saw in my life; the best part of them old soldiers that had served under the king for the Religion all this while."

The envoy was especially enthusiastic, however, in regard to the French cavalry. "There are near six thousand horse," said he, "whereof gentlemen above four thousand, about twelve hundred other French, and eight hundred reiters. I never saw, nor I think never any man saw, in prance such a company of gentlemen together so well horsed and so well armed."

Henry sent a herald to the camp of the allies, formally challenging them to a general engagement, and expressing a hope that all differences might now be settled by the ordeal of battle, rather than that the sufferings of the innocent people should be longer protracted.

Farnese, on arriving at Meaux, had resolved to seek the enemy and take the hazards of a stricken field. He had misgivings as to the possible result, but he expressly announced this intention in his letters to Philip, and Mayenne confirmed him in his determination. Nevertheless, finding the enemy so eager and having reflected more maturely, he saw no reason for accepting the chivalrous cartel. As commanderin-chief—for Mayenne willingly conceded the supremacy which it would have been absurd in him to dispute—he accordingly replied that it was his custom to refuse a combat when a refusal seemed advantageous to himself, and to offer battle whenever it suited his purposes to fight. When that moment should arrive the king would find him in the field. And, having sent this courteous, but unsatisfactory answer to the impatient Bearnese, he gave orders to fortify his camp, which was already sufficiently strong. Seven days long the two armies lay face to face—Henry and his chivalry chafing in vain for the longed-for engagement—and nothing occurred between those forty or fifty thousand mortal enemies, encamped within a mile or two of each other, save trifling skirmishes leading to no result.

At last Farnese gave orders for an advance. Renty, commander of the vanguard, consisting of nearly all the cavalry, was instructed to move slowly forward over the two hills, and descending on the opposite side, to deploy his forces in two great wings to the right and left. He was secretly directed in this movement to magnify as much as possible the apparent dimensions of his force. Slowly the columns moved over the hills. Squadron after squadron, nearly all of them lancers, with their pennons flaunting gaily in the summer wind, displayed themselves deliberately and ostentatiously in the face of the Royalists. The splendid light-horse of Basti, the ponderous troopers of the Flemish bands of ordnance under Chimay and Berlaymont, and the famous Albanian and Italian cavalry, were mingled with the veteran Leaguers of France who had fought under the Balafre, and who now followed the fortunes of his brother Mayenne. It was an imposing demonstration.

Henry could hardly believe his eyes as the much-coveted opportunity, of which he had been so many days disappointed, at last presented itself, and he waited with more than his usual caution until the plan of attack should be developed by his great antagonist. Parma, on his side, pressed the hand of Mayenne as he watched the movement, saying quietly, "We have already fought our battle and gained the victory." He then issued orders for the whole battalia—which, since the junction, had been under command of Mayenne, Farnese reserving for himself the superintendence of the entire army—to countermarch rapidly towards the Marne and take up a position opposite Lagny. La Motte, with the rearguard, was directed immediately to follow. The battalia had thus become the van, the rearguard the battalia, while the whole cavalry corps by this movement had been transformed from the vanguard into the rear. Renty was instructed to protect his manoeuvres, to restrain the skirmishing as much as possible, and to keep the commander-in-chief constantly informed of every occurrence. In the night he was to entrench and fortify himself rapidly and thoroughly, without changing his position.