At the battle of Leipsic, Gustavus Adolphus had 19,000 infantry and 11,000 cavalry; Tilly had 31,000 infantry and 13,000 cavalry. At Lutzen. Wallenstein had 24,000 infantry and 16,000 cavalry in 170 squadrons. The number of guns, too, increased with the introduction of light pieces; the Swedes often had from 5 to 12 guns for every 1,000 men; and at the battle of the Lech, Gustavus Adolphus forced the passage of the river under cover of the fire of 72 heavy guns. - During the latter half of the 17th and the first half of the 18th century, pikes and all defensive armor for infantry were finally done away with by the general introduction of the bayonet. This weapon, invented in France about 1640, had to struggle 80 years against the pike. The Aus-trians first adopted it for all their infantry, the Prussians next; the French retained the pike till 1703, the Russians till 1721. The Hint-lock, invented in France about the same time as the bayonet, was also gradually introduced before the year 1700 into most armies. It materially abridged the operation of loading, protected to some degree the powder in the pan from rain, and thus contributed very much to the abolition of the pike.

Yet firing was still so slow that a man was not expected to use more than from 24 to 36 cartridges in a battle; until in the latter half of this period improved regulations, better drill, and further improvement in the construction of small arms (especially the iron ramrod, first introduced in Prussia), enabled the soldier to fire with considerable rapidity. This necessitated a still further reduction of the depth of formation, and infantry was now formed only four deep. A species of elite infantry was created in the companies of grenadiers, originally intended to throw hand-grenades before coming to close quarters, but soon reduced to fight with the musket only. In some German armies riflemen had been formed as early as the 30 years' war; the rifle itself had been invented at Leipsic in 1498. This arm was now mixed with the musket, the best shots in each company being armed with it; but out of Germany the rifle found little favor. The Austrians had also a sort of light infantry called pandours - Croatian and Servian irregulars from the military frontier against Turkey, useful in roving expeditions and pursuit, but, from the tactics of the day and their absolute want of drill, useless in battle. The French and Dutch created, for similar purposes, irregular infantry called compagniesfranches.

Cavalry, too, was lightened in all armies. There were no longer any men-at-arms; the cuirassiers maintained the breastplate and helmet only; in France and Sweden the breastplate was also done away with. The increasing efficiency and rapidity of infantry fire told very much against cavalry. It was soon considered perfectly useless for this latter arm to charge infantry sword in hand; and the opinion of the irresistibility of a firing line became so prevalent that cavalry, too, was taught to rely more on its carbines than on the sword. Thus, during this period, it often occurred that two lines of cavalry maintained a tiring tight against each other the same as if they were infantry; and it was considered very daring to ride up to within 20 yards of the enemy, tire a volley, and charge at a trot. Charles XII., however, adhered to the rule of his great predecessor. His cavalry never stopped to tire; it always charged, sword in hand, against anything opposing it, cavalry, infantry, batteries, and intrenchments, and always with success. The French, too, broke through the new system and recommenced relying on the sword only. The depth of cavalry was still further reduced from four to three. In artillery, the lightening of the guns, and the use of cartridges and case-shot, now became general.

Another great change was that of the incorporation of this arm with the army. Hitherto, though the guns belonged to the state, the men serving them were not soldiers, but formed a sort of guild, and artillery was considered not an arm but a handicraft. The officers had no rank in the army, and were considered more related to master tailors and carpenters than to gentlemen. About this time, however, artillery was made a component part of the army, and divided into companies and battalions; the men were converted into permanent soldiers, and the officers ranked with the infantry and cavalry. The centralization and permanence of the armed contingent upon this change paved the way for the science of artillery, which under the old system could not develop itself. - The passage from deep formation to line, from the pike to the musket, from the supremacy of cavalry to that of infantry, had thus been gradually accomplished when Frederick the Great opened his campaigns, and with them the classical era of line tactics. He formed his infantry three deep, and got it to tire five times in a minute.

In his very first battles at Mollwitz, this infantry deployed in line, and repelled by its rapid tire all charges of the Austrian cavalry, which had just totally routed the Prussian horse; after finishing with the cavalry, the Prussian infantry attacked the Austrian infantry, defeated it, and thus won the battle. Formation of squares against cavalry was never attempted in great battles, but only when infantry on the march was. surprised by hostile cavalry. In a battle, the extreme wings of the infantry stretched round en potence when menaced by cavalry, and this was generally found sufficient. To oppose the Austrian pandours, Frederick formed similar irregular troops, infantry and cavalry, but never relied on them in battle, where they were seldom engaged. The slow advance of the firing line decided his battles. Cavalry, neglected under his predecessor, was now made to undergo a complete revolution. It was formed only two deep, and firing, except on pursuit, was strictly prohibited. Horsemanship, considered hitherto of minor importance, was now cultivated with the greatest attention. All evolutions had to be practised at full speed, and the men were required to remain well closed up.