Naturally, therefore, by degrees the proportion of firearms in the _battaglia_ (whence comes our modern “battalion”) increased, and the formation of definite fighting units, such as brigades, by Gustavus Adolphus, Maurice of Nassau, and others, began to make the force more capable of direction and control. De Rohan in France, too, devised regiments on what were then scientific principles. His were composed of 600 pikes, 600 musketeers, and 240 swordsmen, and, later, cavalry were placed between these massive battalions. Speaking generally, the artillery was little moved, and remained stationary during a battle. The cavalry charged sword in hand or with pistols, and the infantry received the charge with the pike or partially met it by fire. But with an improved artillery arose also the necessity for ammunition and other supply trains from fixed magazines, and hence more careful strategy based on care for these magazines or “bases of operations,” and regard for the roads “or lines of communication” leading from them to the army, influenced the conduct of campaigns; so also did the introduction of superior organisation. For food supplies, armies on the move were still dependent on the good-will of the people, open markets, or plunder. It was long before the supply of troops formed part of the serious study of the art of war. There was yet but little change in the method of fighting. Artillery as an “arm” was not. Rupert thought still that cavalry was the principal arm and could do anything. Cromwell alone recognised what trained infantry could be made to do.