Prussian Army entering France in 1814
"Since the doing away with tents and the introduction of the system of subsisting troops by compulsory demands for provisions on the spot, the baggage of an army has been very sensibly diminished, and as a natural and most important consequence we look first for an acceleration in the movements of an army, and, therefore, of course, an increase in the length of the day's march. This, however, is only realised under certain circumstances.
Marches within the theatre of war have been very little accelerated by this means, for it is well known that for many years whenever the object required marches of unusual length it has always been the practice to leave the baggage behind or send it on beforehand, and, generally, to keep it separate from the troops during the continuance of such movements, and it had in general no influence on the movement, because as soon as it was out of the way, and ceased to be a direct impediment, no further trouble was taken about it, whatever damage it might suffer in that way. Marches, therefore, took place in the Seven Years' War, which even now cannot be surpassed; as an instance we cite Lascy's march in 1760, when he had to support the diversion of the Russians on Berlin, on that occasion he got over the road from Schweidnitz to Berlin through Lusatia, a distance of forty-five miles, in ten days, averaging, therefore, 4½ miles a day, which, for a corps of 15,000, would be an extraordinary march even in these days.
On the other hand, through the new method of supplying troops the movements of armies have acquired a new retarding principle. If troops have partly to procure supplies for themselves, which often happens, then they require more time for the service of supply than would be necessary merely to receive rations from provision wagons. Besides this, on marches of considerable duration troops cannot be encamped in such large numbers at any one point; the divisions must be separated from one another, in order the more easily to manage for them. Lastly, it almost always happens that it is necessary to place part of the army, particularly the cavalry, in quarters. All this occasions on the whole a sensible delay. We find, therefore, that Buonaparte in pursuit of the Prussians in 1806, with a view to cut off their retreat, and Blucher in 1815, in pursuit of the French, with a like object, only accomplished thirty miles in ten days, a rate which Frederick the Great was able to attain in his marches from Saxony to Silesia and back, notwithstanding all the train that he had to carry with him.
At the same time the mobility and handiness, if we may use such an expression, of the parts of an army, both great and small, on the theatre of war have very perceptibly gained by the diminution of baggage. Partly, inasmuch as while the number of cavalry and guns is the same, there are fewer horses, and therefore, there is less forage required; partly, inasmuch as we are no longer so much tied to any one position, because we have not to be for ever looking after a long train of baggage dragging after us.
Marches such as that, which, after raising the siege of Olmutz, 1758, Frederick the Great made with 4,000 carriages, the escort of which employed half his army broken up into single battalions and companies, could not be effected now in presence of even the most timid adversary.
On long marches, as from the Tagus to the Niemen, that lightening of the army is more sensibly felt, for although the usual measure of the day's march remains the same on account of the carriages still remaining, yet, in cases of great urgency, we can exceed that usual measure at a less sacrifice.
Generally the diminution of baggage tends more to a saving of power than to the acceleration of movement."
Interestingly, Clausewitz claims that although armies both lightened their baggage load, reduced the number of horses as a result and switched from magazine supply to local foraging, there was not much increase in speed or distance marched in a day between the Seven Years War and the Befrieungskrieg of 1813. The result was a more consistent marching pattern and freedom to operate. However it should be remembered that Frederick the Great had by far the most mobile of the armies of the Seven Years War and his march from Saxony to Silesia was supplied by depots along his route largely through Prussian territory, not an adavnce into enemy territory. His other generals, Prince Ferdinand of Brunswick and Prince Henry were more constrained in their operations and the French armies and the 'Reichsarmee' were slower still.