I think we must give credit to France also. They are probably one of the most influential nations in the world, politically and ideologically speaking. Socialist parties (and also intellectuals, writers, artists, actors and the like) from around the world, especially Latin American, but also all over Europe and Africa, they all look up to France's modern social democrat model and their tendencies in public policies and good government.
And they are a proud and thinking people, a country accustomed to debating and discussing, and much like America, feel that they have an important role to play in Europe and the world (I sometimes believe that American actually inherited their love for debating and discussing from some scattered and not so many French ancestors, please correct me if I am wrong on this).
And so I believe that for these and other reasons it is that only France has the leadership in Continental Europe to promote, support or even wage a war, and only France can guarantee that other nations like Spain and Germany along with all or most of Europe will join a coalition or support a war with troops, equipment and euros, lots of them.
Germany, the most economically influential nation in continental Europe cannot promote, support or wage any wars by itself because of it traumatic military past, something they have not come to terms with, apparently.
Holland, Belgium, Italy, Spain, Poland, Greece, they can all promote, support and help the Americans, but lack the political leadership the France has.