Question for WWI campaigns

[Sharky]

Hi Guys,

I have some question for the wwi campaigns in France and Prussia.

In the southern part of the front, as France i have a big river which, at least my cavalry, even in travel mode, cannot cross. However i have "obstacle" in front of those rivers. I'm not sure how to defend as France, big rivers cannot be crossed ? Like by anything ? 

Which would mean i can have few troops across the river right ? 

But what are the obstacle for ? does it just slow movement of enemy units ? should i put troops on obstacle or on the other side ? Does the stack limit on obstacle is lower than in open ground ?

I know that the southern part of the French army was supposed, according to the german plan, to advance in Germany, thus making the front larger and taking troops away from the main thrust, i'd like to take defensive positions on the south but don't know how best to use obstacle and big rivers. Any difference between "rivers" and "canal" by the way ?


Also, playing scenario "A", it look like I have a lot of troops aiming at the north at the beginning of the campaign, should i sent more armies to the south than the disposition at the beginning of the scenario is sending ? When looking at the scenario from the german point of view there doesn't seem to have that much german armies in the north.


thanks for any help !