By the beginning of the 18th Century the military leaders of major European powers had already been attempting to find practical ways to employ firepower effectively on the battlefield for several hundred years, and much progress had been made prior to the advent of the flintlock musket. The Swedish warrior-king Gustavus Adolphus (1596-1632) made important advances in tactics during an earlier period. Gustavus redesigned the fighting formation of his infantry at the start of the Thirty Years War (1618-1648) in order to take advantage of efficiencies he had developed in the use of the old matchlock musket that increased its rate of fire in the hands of Swedish musketeers.

Gustavus developed a lighter matchlock and other innovations, like the cartridge, that made loading and firing easier, thus doubling the rate of fire of his musketeers. This increase in rate of fire made it possible to reduce the number of ranks in a battalion's fighting formation to six, which widened its frontage so that more muskets could be fired at one time in salvos, or "volleys." This change of formation created a more linear, less columnar, maneuver element.

The Imperial armies opposed to the Swedes still fought in massive infantry formations called tercios (a Spanish word for regiment), consisting of 1500 or more men formed in a huge block about 50 men wide and 30 deep. This had been the standard infantry formation for many decades. Pikemen formed the mass of the tercio, with a belt of musketeers surrounding the column of pikemen, or formed at its corners. The tercio was primarily a shock formation, a huge iron tipped column of men to be launched upon the enemy to destroy him with cold steel, or a solid defensive pike formation without flanks that could protect the musketeers sheltering within it from hostile cavalry.

Gustavus countered the tercio with smaller, more maneuverable infantry formations designed to take advantage of firepower. Gustavus organized his infantry in 500 man battalions (called squadrons) that were easier to maneuver on the battlefield than were larger tercio formations. A Swedish battalion was about 80 men wide and six men (ranks) deep. Three battalions formed a "brigade," which was usually deployed in a triangular formation, with one battalion in front, the other two behind and to right and left of the forward battalion, to support it on the flanks.

Gustavus attached light field pieces to his battalions to increase firepower, thus being the first to employ "battalion guns." However, in spite of this emphasis on firepower, about one third of each Swedish infantry battalion was still armed with the pike. The musketeers needed the pikemen to protect them from horsemen. A musketeer with an empty matchlock was vulnerable to cavalry because he had only a sword or clubbed musket with which to defend himself.

As the 17th Century progressed, the major European powers adopted the basic fighting formations invented by Gustavus, some quickly, others slowly, the French, Austrians, and very backward Russians being the slowest. To increase firepower the tendency was to reduce the number of pikemen in the battalion in order to increase the number of men armed with matchlocks. By 1685 pikemen constituted only about twenty percent of the fighting strength of the typical battalion, and now their only function was to attempt to protect the gun-armed men from cavalry attack. No longer did they attack the enemy en masse to attempt to overcome him by "push of pike." The pikemen themselves seem to have understood the waning importance of their weapon. Some report that they discarded their pikes during battle as soon as it was possible to pick-up a matchlock from a musketeer who was out of action.

Unfortunately, this reduction in pikemen had a detrimental effect on the ability of a battalion to resist attack by cavalry. The small body of pikemen remaining could not always protect the musketeers, and although numerous expedients involving the deployment of pikemen within the battalion were tested to attempt to correct this problem, none succeeded. Another unfortunate result of the need to maintain some pikemen in a battalion was that all the complicated movement and deployment processes necessary to coordinate pikemen with musketeers in the same formation continued to impede the ability of the battalion to maneuver.

For these reasons, as the 17th Century progressed, battles tended to be contests in which opposing infantries wore each other down in prolonged firefights, then the cavalry charged home to decide the issue. Hence, though infantry remained an important and numerous part of an army, cavalry became the decisive instrument of victory.

More From Breitenfeld to Waterloo The Origins of Napoleonic Infantry Tactics

Introduction
Infantry in the Early Musket Era
The Flintlock Musket Revolutionizes Warfare
The "Order of Battle" During the Classical Linear Period
Firepower vs. Shock
Further Reading