As for the American Revolution and the War of 1812 (well 1812-1814), I had a History Professor who called that
"The 13 Stars War" and "The Empire Strikes Back."
But back to the French, they just have not got a great record since the end of the Napoleonic Wars. Starting with the first defeat of Napoleon and his final defeat at Waterloo after the 100 days, they have been beat up by everyone from the Mexicans (what do you think Cinco de Mayo is all about) to the Vietnamese.
Oh, I don't know. In general they did better in the Crimea than the British, or at least had fewer major screw-ups (as General Canrobert said while watching the Light Brigade charge to its destruction, "
Cest magnifique, mais ce nest pas la guerre." That any of them were able to return from the charge was largely due to the fact that French troops had in the meantime taken the Fedouikine Heights, decreasing the amount of artillery fire by about 1/3rd.
As to Mexico, nah. It was Napoleon III who decided to pull out the French troops and leave Maximilian in the lurch, owing to Napoleon's wish to have more troops facing an increasingly belligerent Prussia as well as US resistance to French 'meddling' in the western hemisphere (i.e., the Monroe Doctrine), that brought about Maximilian's fall.
As for the rest, France was as successful as every other western colonial power in the 19th century, which was hardly surprising when considering the firepower imbalance between the western troops and the natives.
That they failed to maintain their hold on these colonies in the aftermath of WW2 was par for the course in the de-colonisation effort, and they were as successful in Algeria as the British were in Malaya. Both left because the cost of staying was judged too high, politically and/or financially. It took DeGaulle to get them out of Algeria, and he had to survive several assasination attempts as a result (see Frederick Forsyth's "Day of the Jackal" for a lightly fictionalised example).
Paris was taken twice in 100 years by the Germans; 1870 when Napoleon III found out that German Krupp breach loading steel cannon beat French brass muzzle loaders
To which can be added the Prussian advantage wth their standard infantry weapon, the needle gun. But the main advantage that Prussia had was their General Staff system, which was undoubtedly in advance of the world at the time. Unfortunately for Germany, after Bismarck her General Staff remained first class at operational matters, but Germany's strategic abilities were just about at the bottom of the list, joined there by Italy and Japan in WW2.
and in 1940 when they found out that the Maginot line could not be taken by a frontal assault, but you could take a side trip through Belgium and drive around it.
True, but that was an issue of lack of political will on the part of the French legislature to complete it the rest of the way, not an inherent failure of the line or the thinking behind it. It worked just as intended, allowing the french military to economise in manpower. It's just that the Germans were ahead of everyone else in their staff work, command and control and especially doctrine.
1914-1918 was a near run thing, but for a few mistakes and lucky breaks, the Germans might have marched in Paris in 1914 or 18. But contrary to what many American think, US troops did not win that war, we just convinced the Germans that they couldnt win.
No argument there. Fortunately, the Germans managed to make so many strategic blunders they lost in both WWI and WWII. Good thing for the allies the Russians were around in both wars, especially the 2nd. Failing the latter, short of the atom bomb there's no way the western allies would have defeated the Third Reich. As it was, the Wehrmacht suffered 70% of its losses against the Soviet Union, and never had less than 60% of their forces on the eastern front from the time they invaded. It's scary to think what might have happened on D-Day if the coastal troops had been high quality, instead of the stomache, ear and Osttruppe units actually manning most of the fortifications.
Guy
As to Waterloo and Trafalgar, yep, they lost. Of course, it took most of Europe about 20 years to defeat them, and the amazing thing about Waterloo is that Napoleon was able to re-constitute a French army to fight for him in such a short time after his escape from Elba. Even so, it took the combined efforts of the Brits, Germans and others to win Waterloo; Britain certainly couldn't have done so alone. 
