In the early sixteenth century, when the _Company_ was only an administrative unit, the _Battaglie_ were its tactical subdivisions, and formed small units fighting separately. Hence _Battaglione_, “the great battaglia,” was the name given to a large fighting unit and consisting of a mass comprising several Regiments and some thousands of men. This “Battalion” was gradually diminished in size, to meet changes in tactics which demanded a more flexible formation for mobility, and a smaller target, less vulnerable to the rude artillery of the day. The experience of the more successful leaders pointed eventually to forming a Battalion of a few hundred men, so that two or three could be furnished by a Regiment, instead of forming a huge Battalion of several Regiments. The fact that sometimes the Regiment formed only one Battalion accounts for the constant confusion between the two terms, and their indiscriminate use even to-day. SPANISH INFANTRY--SIXTEENTH CENTURY The remarkable efficiency of the Spanish Infantry which was fighting against Maurice for the domination of the Netherlands should not be overlooked. They had, besides musketeers, bodies of swordsmen with bucklers, active enough to overcome the pikemen. The Spaniards were the first to establish depôts for their army in war, where recruits could be trained by a few old soldiers. Their Regiments were of some 1,700 men, and the Companies varied from 150 to 300. The good order of the Spanish Army, and its strict discipline, were its most remarkable features. In the latter half of the sixteenth century the Spanish Infantry was undoubtedly the best in Europe. INFANTRY UNDER GUSTAVUS The next development of Infantry is seen in the Swedish Army as organized in the Thirty Years’ War by the great Gustavus Adolphus, King of Sweden. Its efficiency and success made it the model of the organization of all the armies in Europe, and they still retain its main features. Gustavus modelled his army on that of Maurice, but made many improvements in it. His purpose was to increase mobility, and to adopt a definite organization of units. With the first object, he lightened the musket, so as to do away with the cumbrous rest, and increased rapidity of fire by adopting a cartridge to hold the powder. He added to the Musketeers till they equalled the Pikemen, and improved the mobility of the latter by shortening the pike. As regards organization, he adopted Brigades much smaller than those of Maurice, and made them a definite unit of two Regiments of Infantry, as they still are in every foreign army. The Regiment had always been the administration unit, and the Battalion the tactical unit. Gustavus definitely fixed the size of the Battalion, two of which formed a Regiment. Here we find the origin of the two-Battalion Regiment, which was universal in Europe for the next hundred years.