In the first half of the seventeenth century the genius of Gustavus Adolphus gave a new value to land ordnance. He made it mobile. He divided his artillery into two categories, Siege and Field, and for the latter devised the famous light “leather guns” which, operating in mass on certain points, had an important effect on the issue of battles. But after his death at Lützen in 1632 the effort to attain mobility relaxed; an increase in the strength of powders at this time rendered the possibility still more remote; and it was not until the following century that the Prussians, under Frederick the Great, evolved a satisfactory light artillery. Both in Prussia and in Austria great efforts were made, in the middle of the eighteenth century, to evolve a mobile and efficient ordnance. The Seven Years’ War found the former state experimenting with pieces varying in weight between eighty and a hundred and fifty times the weight of their ball; and in 1762 a certain French observer, who was destined to become famous as one of the great artillery reformers of all time, wrote letters from Vienna describing the fine qualities of the Austrian service: with its pieces all sixteen calibres in length, all 115 times their balls in weight, all bored to their true nominal dimensions, and firing accurately spherical balls of correct size, with a small windage and a powder-charge of less than one-third the weight of the shot. In the years immediately following the close of the Seven Years’ War the lessons learned at Vienna were translated into practice in France. By 1765 Gribeauval had begun his reorganization of the French material. In order to obtain mobility he made new models of 12, 8, and 4-pounders, very plain, unchambered pieces, each eighteen calibres in length, 150 times its own shot in weight, and firing well-fitting balls with unprecedented precision, with powder-charges of one-third the weight of the balls. Limbers, in the form of small-trucked bogies, had been in occasional use ever since the sixteenth century. Gribeauval introduced large-wheeled limbers, and dragged his 12-pounders by six, his 8- and 4-pounders by four horses. From the number of horses, as compared with that of the edict of Henri II, one can measure the progress made in two centuries. The whole of Gribeauval’s material was designed to afford rapid transport and rapid and accurate fire; interchangeability of wheels and other parts formed a novel and important element of the standardization which he accomplished. Iron axle-trees, cartridges (used with effect by Gustavus in the preceding century), elevating screws, tangent scales, and other improvements were adopted under his authority. But, “Gribeauval could not force on France the two great inventions of the century--the limber-box and the Horse Artillery.”[68]