The army corps composed of infantry divisions of the First Series went to war in the middle of October 1914.1 Soon thereafter, the depots that had formed the component battalions, batteries, and squadrons of those formations had begun to build elements for a new series. Not nearly as famous as their immediate predecessors, the nine divisions of this Second Series were nonetheless formed in very much the same way.2
The infantry, cavalry, and some (but not all) of the artillery components of the Second Series formations were created in much the same way as their counterparts of the First Series.3 Some of the batteries, however, were made up of elements withdrawn from units then serving at the front. (This often took the form of the removal of a two-piece section from a six-piece battery, thereby making the former available for the creation of new units while turning the latter into a four-piece battery.)4
The latter technique played a much bigger role in the raising of the Third Series of new infantry divisions, which took place at six locations on the Western Front in March of 1915. All of the field artillery batteries assigned to these six new divisions were assembled from elements taken from six-piece batteries already serving at the front. Similarly, all of the infantry regiments and cavalry squadrons of these divisions were existing units that had been serving at the front since the start of the war.5
Prussia contributed ten of the thirteen divisions of the First Series. Württemberg, Saxony, and Bavaria provided, respectively, the 53rd Reserve Division, the 54th Reserve Division, and the 6th Bavarian Reserve Division. The 6th Bavarian Reserve Division did not go to the front until the very end of October 1914.
The collection of documents consulted in the course of writing this post did not contain the actual letter ordering the formation of divisions of the Second Series. It did, however, contain several documents that made explicit reference to this order (Kriegsministerium M.J. Nr. 11204/14 A.1., dated 18 December 1914.) See, among others, Gardekorps. Stellvertr. Generalkommando. Sekt. Ia Nr. 31007, dated 19 December 1914 and a very detailed warning order: Kriegsministerium, letter MJ 11007/14 A1 Geheim, dated 13 December 1914. All of these letters can be found in the NARA M-962, Roll 3 (folder marked Akten des Königlichen Militär-Kabinets Abteilung I betreffend Mobilmachung 1914, 1. Allgemeines, Band 1A.)
Prussia provided eight of the divisions of the Second Series. (The senior of these divisions was the 75th Reserve Division, the junior the 82nd Reserve Division.) Bavaria provided the ninth division. (This was the 8th Bavarian Reserve Division.) Wrisberg, Heer und Heimat, page 24 and Cron, Geschichte des Deutschen Heeres im Weltkrieg, pages 99, 146, and 147.
For an example of how this was done to assemble six batteries for one of the two field artillery regiments of the 80th Reserve Infantry Division, see Karl Retzlaff, Reserve Feldartillerie Regiment Nr. 65, (Oldenburg: Gerhard Stalling, 1923), page 1.
Prussia, Kriegsministerium, MJ. Nr. 3844/15 A1, Geheim, dated 1 March, 1915, NARA, M-962, Roll 3.