These aims it was sought to effect by means of a series of circular railways, or "rings" of railways, joining up the existing lines, and allowing of the transfer of military transport from one to the other without coming into Paris at all. An "inner" circular railway ("Chemin de Fer de Petite Ceinture") had already been constructed within the fortifications prior to 1870, and this was followed in 1879 by an "outer" line, ("Chemin de Fer de Grande Ceinture"), which provided a wider circle at an average distance of about 20 km. (12½ miles) and established direct rail connection, not only between a large number of the more remote suburbs, together with the different trunk lines at a greater distance from the city, but, also, between the various forts constructed for the defence of Paris. These circular railways were, in turn, succeeded by a series of connecting links which ensured the provision of a complete ring of rail communication at a still greater distance around Paris, the towns comprised therein including Rouen, Amiens, La Fère, Laon, Reims, Chalons-sur-Marne, Troyes, Sens, Montargis, Orléans, Dreux, and so on back to Rouen. Within, again, this outermost ring there was provided a further series of lines which, by linking up Orléans, Malesherbes, Montereau, Nogent, Epernay, Soissons, Beauvais and Dreux, established additional connections between all the lines from Paris to the north and the east of France, and gave increased facilities for the distribution in those directions of troops arriving at Orléans from the south-west, this being once more done without any need for their entering Paris or even approaching it at a closer distance than about forty miles. Orléans itself was recognised as a point of great strategical importance in regard to the movement of troops, and it was, accordingly, provided with a number of new lines radiating therefrom, and establishing better connections with other lines. Tours and other centres of military significance, from the same point of view, were strengthened in a like manner. At important junctions, and notably so in the case of Troyes (Champagne), loop lines were built in order that troop trains could be transferred direct from one line to another without stopping, and with no need for shunting or for changing the position of the engine. In the direction of the eastern frontier the line from Verdun to Metz was completed, and by 1899 the three routes which could alone be made use of in 1870-71 had been increased to ten. Most of them were provided with double-track throughout, and all of them were independent of one another, though having intercommunication by means of cross lines.