The debate seems to be caught between two issues
- Practice of only two ranks firing (but the third being some form of reserve and/or skirmishers
- Deliberate intent to deploy the line (ie Musketeers and Grenadiers) in two ranks (i.e. with the “third rank” then extending the frontage of the line)
Enclosed is some background information you may find interesting. Much appears elsewhere on this site and I am indebted to other contributors for much of the details.
The translations are “free” translations
- Prussians used two ranks during Seven Years war (reference missing) – but this appears as a consequence of need due to shortage of manpower, not regulations.
- There is however a formal recognition that a two ranks line may be appropriate as the 1788 Reglement for Fusiler (ie light infantry is to deploy in two ranks), the Reglement for the line notes …All grenadier and musketeer companies will always form (unless it is ordered otherwise, for particular reasons, in three ranks.
- It appears 2 rank formations were used in the 1790’s as Wrede (citation missing) noted the use of two ranks for the Prussians in this period. This was used to justify the Bavarian Regulations being modified for their Line infantry to operate in two ranks from 1804. Note it is not clear if this is a case of two ranks (i.e. like the British were doing in practice) or that only two ranks are in the “firing” line and the third rank is used as skirmishers, or more formally held back as a reserve. See also implication in Ruchel’s instructions.
- In 1806 some, but not all, infantry of the Prussian army put two ranks into practice as the standard deployment and the evidence suggests this has been used in campaigns of the 1790’s. Rüchel in his instructions dated 1 October 1806 notes “The third rank of the infantry is completely unnecessary. Its fire not only goes into the air, but also intimidates the soldiers of the first rank. The experience of three campaigns - which the King’s troops served with glory and honour - that two Prussian ranks are completely sufficient to defeat the enemy. Yet while on campaign forming in two ranks with battalions at full strength, the voice of commanders are not loud enough to be heard fully and the movements become slow. Therefore, I order that the infantry regiments form themselves in three battalions.
- first battalion of 3 companies in 6 platoons;
- second battalion of 4 companies in 8 platoons;
- third battalion of 3 companies of 6 platoons.
- Corroborating information for two ranks is Borcke, his regiment was deployed in two ranks (page 27, 29, 31) but not clear if reformed to three battalions. Inconclusive information comes from Jany - the Regiment Winning’s diary notes the reformation into three battalions, use of two ranks does not appear to have been mentioned.
Some sources on this are
Höpfner’s (1850) Der Krieg von 1806 und 1807, vol 1,
- Rüchel's instructions dated "Mühlhause den 1. Oktober 1806" (Beilage D)
Höpfner’s (185?) Der Krieg von 1806 und 1807, vol 3,
- King's instructions dated "Osterode, den 23. November 1806" (Beilage F)
- Does not appear to be available on Google
von Borcke, Johann (1888) Kriegerleben des Johann von Borcke,
Jany, Curt (1901) "Die Gefechtsausbildung"
- (1901) Urkundenliche Beiträge und Forschungen zur Geschichte des Preussischen Heeres Issues 1 to 5
Prussia (1788) Reglement für die Königlich Preußische Infanterie,
- Line or light regulations do not appear to be available on Google – note clear if these are also two separate documents. Available in British Library