Britain and France are improved their cooperation in national security matters with the signing of treaties. It's an odd piece of European cooperation (interesting commentary here).
Historically, Germany and France did cooperate closely to push forward European policy and unification. The grand strategy motivations were different, but it did obviously work out quite well - until the issue got overstretched with the common currency.
European unification seems to be at a saturation point with the Lisbon treaty, an ill-functioning common currency and with many new Eastern European members which have set back the European Union in regard to political diversity to the 60's.
The German-French cooperation seems to lose relevance on this background, unless we get some really bright ideas. The rather erratic character of France's president Sarkozy contrasts a lot with the Germany's passive conservative chancellor Merkel and adds to the forces against a great push forward.
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The British-French cooperation might be interpreted as a kind of successor for the German-French cooperation, except that they seem to be focused on external affairs (the military) and their cooperation primarily looks like a bilateral cost-savings measure.
Their cooperation -if it turns out to work with little friction- could nevertheless become a factor in European politics in general.
The largely impractical and overly bureaucratic attempts of full European cooperation on defence and of a common security policy might become overshadowed by the British-French example. The new entente might also influence the way how other European nations think about national security - less peacekeeping and conventional deterrence, more nuclear thinking, more naval and more expeditionary.