"Did we really want to allow the Germany of Bismarck to replace France of Napoleon?"
Germany as created by Bismarck but who had long been out of the picture before 1914. His removal allowed a reckless, feckless and paranoid Kaiser along with a confident and strident German Military & Industrial complex to exercise too much power with insufficient political control over it, even though Germany was a Democratic Nation.
We had no interest in the Prussia/France ding dong in 1871. The loss of that War was one reason why France sought Allies leading to the Grand Alliance which, combined with our ancient pledge to protect Belgium, led to a War involving the British Empire.
France wanted enhanced protection, perhaps revenge for its earlier "humiliation" from having to pay reparations and in the loss of Alsace and Lorraine A bit like the reasons Hitler used to get back what Germany lost in 1918. So other than becoming involved in the ancient Franco German enmity what did our involvement achieve?
Niall Ferguson's programme can but speculate on the possible outcomes had we stood aside at least in 1914. However, years of ill feeling had been allowed to develop by then despite the close historical ties between both Britain and Germany. Such that even our dislike of France was replaced by that of a Nation that we had always had much in common with.
A Century on it all seems like a waste but then don't all wars once they end even if we "win" and win we did. Germany was collapsing into Revolution by 1918 with the Kaiser exiled. Hitler used the Armistice to peddle his "undefeated in the field" lie.
What would our fore-bearers think now we zoom around in Audi's, BMW's and VW's can shop at Aldi/Lidl and have no cultural issue with either?