Again, they charged; again, with sabering fury. And, again, were driven back.

The infantry tercios lumbered nearer. The cavalrymen, seeing them come, were driven into yet another headlong charge. For them the victory! Not those wretched footmen!

No use. The tercios crept forward.

Finally, the imperial cuirassiers abandoned the saber and fell back on the wheel-lock pistol. They began wheeling in the caracole, firing their pistols at a distance and circling to reload. Those men were mercenaries, when all was said and done. They could not afford to lose their precious horses. And they had already learned, as Pappenheim's men before them, that the Swedish tactic against heavy cavalry was to aim arquebus and pike at the horses. They had been trained and instructed in that method by their king. Gustav Adolf had long understood that his Swedish ponies were no match for German chargers. So kill the chargers first.

The tercios advanced across the battlefield, at the oblique. Grinding toward the Swedish left, now bent at a right angle away from the original battle line. Like a glacier, those seventeen tercios seemed. Slow-and unstoppable.

But that too was illusion. The glacier was about to calve, under gunfire it had never before encountered. The finest artillery in the world was on the field, that day, under the leadership of the world's finest artillery commander. Torstensson had needed no orders. His king had not even bothered to send a courier. The young artillery general, as soon as he saw Gustav sending Hepburn and Vitzthum's men to reinforce Horn, had known what was coming. For all the Swedish king's strategic caution, he was invariably bold on the battlefield. Torstensson knew that a counterattack was looming, and it was his job to batter the tercios in advance. Batter them, stun them, bleed them. Like a picador in a bullring, he would weaken the beast for the matador.

"Swivel the guns!" he roared. Torstensson, afoot as always in a battle, raced to stand at the front. It was a day for hat-snatching, it seemed. He tore his own from his head and began waving it.

"Swivel the guns!" That second roar caused him to choke. There had been a drought in the area that summer, and the plains were dry. The dust thrown up by thousands of horses caught in his throat. Using his hat as a pointer, Torstenson silently emphasized his command.

His gunners were all veterans. Immediately, grunting with exertion at the levering spikes, they began swiveling the field guns to bring enfilade fire on the tercios crossing in front of them.

There were two types of guns in the batteries. The majority, forty-two of them, were the so-called "regimental guns." Three-pounders: the world's first genuine field artillery. These cannons were made of cast bronze, with a light, short barrel to make them easily maneuverable in the field. The Swedes, after experimenting, had discovered that by using a reduced powder charge the guns could be fired safely time after time. They were of no use in a siege, but were superbly effective on the battlefield.

The heavier field guns were twelve-pounders. Gustav Adolf had simplified his ordnance drastically over the past years, based on his experience in the Polish wars. He brought only three sizes of cannon with him to Germany-the light and heavier field guns, and twenty-four-pounders for siege work. He had dispensed altogether with the forty-eight-pounder traditionally used in reducing fortifications.

The three-pounders were firing within a few minutes. The twelve-pounders quickly followed suit. By the time Tilly's infantry neared the angle in their opponent's line, they were coming under heavy fire from the Swedish artillery.

Understanding that the battle had reached a critical moment, Torstensson was ordering a rate of fire which was just barely short of reckless.

"I want a shot every six minutes!" he bellowed, trotting up and down behind the line of his guns. "Nothing less!" He practically danced with energy, waving his hat. "I'll hang the crew who gives me less!"

His men grinned. Torstensson always issued blood-curdling threats on the battlefield. And never carried them out. Nor was there any need. His men were well into the rhythm again, and had already reached the round-every-six-minutes rate which was considered the maximum of the day.

They could not keep that up forever, of course. The problem was not with them, but the guns. The cannons had been firing for three hours, now. Each of them had discharged close to thirty rounds. After another ten rounds, at that rate of fire, the guns would be so hot that they would have to sit idle. For at least an hour, probably, to allow the barrels to cool enough to be used safely.

"Let the blasted things melt!" roared Torstensson. He flung his hat toward Tilly's tercios. "I want those battles broken! Broken in pieces, do you hear?"

The grins faded from his gunners' faces. Torstensson was dead serious now, they knew. If need be, he would keep the guns firing long past the point of safety. The artillerymen sweated through the rhythm. So be it. If a crew died because of a burst cannon, so be it. Torstensson himself would pick up the rammer.

Cannonballs began tearing great holes in the tightly packed Catholic formations. Torstensson's gunners were the finest in the world, and they knew what their commander wanted.

"Grazing shots!" Torstensson slammed the flat of one hand into the other, as if skipping a stone off a lake. "Nothing but grazing shots! I see two balls in a row plunge into the ground I'll hang the crew! Hang 'em, do you hear?"

His men laughed. Another idle threat. Almost every round they fired was the good artilleryman's sought-after "grazing shot."

The "grazing shot" was useless against fortifications, but against men in the field it was devastating. The balls landed dozens of yards in front of their target and bounced forward at a shallow angle, instead of burying themselves in the ground. From that first bounce, their trajectory was at knee-to-shoulder height. The cast-iron missiles caromed into the packed ranks of the enemy like bowling balls-except these balls destroyed men instead of knocking down pins. Even a three-pound ball, in a grazing shot, could easily kill or maim a dozen men in such close ranks. The twelve-pounders wreaked pure havoc.

Torstensson's artillery was ripping the tercios like an orca ripping flesh from a great whale. Blood began settling the dust. The men in the rear tercios slogged through mud left by their comrades' gore-and added their own to the mix. Graze, graze, graze, graze. Death wielded his sickle that day, and mercilessly.

Not even Tilly's men could shrug off that kind of fire. Courageous as always, the recruits following the lead of the veterans; they obeyed their orders and plowed stubbornly toward the angle in the Swedish line. But their formations became more and more ragged and broken. Pikemen were being injured by the weapons of their mates, now, as men stumbled over corpses and lost control of the great blades.

Tilly saw, and grew pale. Near the front of his advancing tercios, he reined in his horse and stared back at the carnage.

"God in Heaven," he muttered. Wallenstein had tried to warn him of the Swedish artillery. Wallenstein-that black-hearted Bohemian! Aye, he-and a dozen Polish officers in Tilly's service. But Tilly had not believed.

"God in Heaven," he muttered again. For a moment, he thought of changing his attack. Wheeling, and driving down on those cursed guns.

Wheeling…

Tilly dismissed the notion instantly. His battles did not "wheel." Could not wheel. They were instruments of crushing victory, not clever maneuver.