http://tvtropes.org/pmwiki/pmwiki.php/Main/CheeseEatingSurrenderMonkeysThe Anglophone stereotype that France sucks at war and surrenders at the drop of a hat... and needs the Anglophone countries to save them!
One would suspect this trope came about due to the fact that, for about the past 200 years, France has had a rough recent record, perceived to have lost or needed to be bailed out of all four of the major wars it has participated in (The Napoleonic Wars, the Franco-Prussian War, the First World War, and Second World War). Funnily enough, this trope only came to prominence in 2003, following France's vociferous objections to the American invasion and occupation of Iraq. While it's true that there was an under-current of 'the French are cowards' before, the prior focus was mainly on their perceived lack of gratitude.
Regardless, the perception of France as a nation of cowards incapable of winning a war could not be further from the truth.
France is one of the largest and most powerful countries on the continent, and it didn't get that way because it was bad at war. The only reason why France isn't a Europe-sized blob is simple: everybody has ganged up on the French at some point in time. Even then, their considerable resources and enormous populationnote up until the mid-19th century meant that they could recover from wars more quickly than their rivals, who sometimes nearly bankrupted themselves trying to keep up with French military spendingnote . By the time Napoleon Bonaparte was finally defeated and removed from power by the Seventh Coalition, the French had been at war with themselves and everyone else for over twenty years, during which they had managed to conquer most of Europe, fought countless battles, and generally left the continent in a giant mess.
Traditionally, France was the military terror of Europe. Today, in addition to maintaining Western Europe's largest military, the country also possesses the third largest nuclear arsenal in the world. Saying that the French have a considerable appetite for war is not an exaggeration: they invested much energy in developing new methods of waging war. They wrote many, many books on waging war. From armoured knights and castles, to muskets and cannon, much of what we associate with medieval and gunpowder warfare came from France. Their enthusiasm for fighting only became dampened by the end of World War I. Over the course of four years, roughly 1.4 million French soldiers died in combatnote , with another 4 million physically (and mentally) scarred by the horrors of industrial-age warfare. France had lost so many men that, when World War II came around, the country had barely managed to recover: the population of France at the time was exactly the same as it was in 1914.
Basically it's no coincidence that most English military terms are actually French words, such as "Artillery," "Battle," "Siege," "Cavalry," "Armor," and many more. Given the sacrifices made during the great wars of the 20th century, any (serious) insinuation of cowardice is both erroneous and disrespectful.
For reference, the phrase "Cheese-eating Surrender Monkeys" was coined in 1995 by Ken Keeler, a writer for the television series The Simpsons.