France opening strategy in Historic World War.

I'd ally with Germany. With Germany and maybe GB on your side you would be unchallenged in Western Europe, with Spain and Italy presenting little of a threat.

Alternatively, I've seen France do well when allied with Italy against Germany, provided they work together.

France is in a very central position and has lots of powerful neighbors, so good diplomatic skills are the key to victory here. If either Germany or Italy attack you, take advantage of your defensive positions along your borders and wear them down with artillery and bombers while they crash into your bunkers like it's Verdun all over again. Make sure to have either AA or Fighter units as Germany has a good number of bombers early-game.

Check if germany is new. If he is new, move your troops to the magniot line and provoke germany to attack you. If he does you will win due to your forts. The key with france is to be patient and use your forts.

I once defeated both germany and italy as france by staying on the defensive in my forts, and then attacking once they have lost many troops.