During the sixties the French military planners uder Marshal Niel developt several attack plans if a war with Prusia would brake out.
The first plan was a rapid attack in to the south of Germany forcing neutrality of the Southern German States Baden, Wurtenberg and Bavaria, before the Prusians could complete their mobilisation.
When it become clear that there was a large support in Baden, Wurtenberg and Bavaria for a united Germany and that these states probably would not be neutral in a war between Prusia and Franche, likely supporting Prusia, this plan was changed
The second plan was a very defensive plan, the whole army would concentrate on the line Thionville to Strassbourg. The army should take defensive positions dig in and wait on the advancing German armies. One army should be in reserve in the North near the border with the Netherlands to cover an surprise advance of Prusian army through this country.
This plan was from a military point of view, considering the larger Prusian army, the wisesed but did not stroke with the French military doctrine of the day which was ‘elan’, full bravore attacking the enemy.
A thrird plan evolved, which was the most ambitious of all. This very ambitous and risky plan was a combination and further development of the prevouis plans.
The French army would be devided in 3 groups. One army group would take defensive positions on the line Thionville to Strassbourg and check advancing German troops.
The second and thrd would violate the neutral Netherlands and make a sweep throug the south of this country and then crosses the border with Germany and advance into the Rhine land.
Despite the risks and the havy reliabitily on logistics it was considered as a very feasable plan. The defences of the Netherlands were heavy neglected over decades, how ever there was a start of a modernisation program for navy and army, it was estimated that the army of the Neterlands was not a big issue to worry about.
After declaration of war by Napoleon III the positions were taken and mobilisation mechanisms started.
The first army, some 150000 men under command of Marshall Bazainne, crossed the Netherlands border on the 28th july from Maubeuge towards Charleroi- Brussels. The second army, 100000 mencommanded by Marshall Mac-Mahon, marched from Charleville towards Liege Maastricht.
The third army some 50000 men ready under command of Marshal Canrobert, dug them self in , on the line Thionville - Strassbourg and would receive more men during the mobilisation.