That is a very forced interpretation. Britain was not challenging France. The height of French power in terms of relative polarity was the early 18th century,

That is a very forced interpretation. Britain was not challenging France. The height of French power in terms of relative polarity was the early 18th century, not Napoleon (by that point, Europe was multipolar). Spain imploded, the Netherlands were imploding (connected to the split and decline of Habsburg), England was still emerging...but the key point about Europe, geopolitically, is that it has been multipolar since the fall of the Roman Empire (in terms of relative power, Britain came closest to domination but never sought preeminence in Europe, the foreign policy of Palmerston was pretty important in this). I don't think Germany was challenging Anglo-American supremacy in WW2. For one, Hitler assumed (correctly, for the most part) that America wasn't terribly bothered about Europe. For two, Hitler also believed that Britain was the natural ally of Germany...until war occurred. WW2 was far more about Hitler's bizarre theories about race and what was happening to the East (Napoleon was France's Hitler...right man, right place but trying to do something that was basically impossible in Europe). WW1 is probably more unclear because Germany did things, like building up their navy, that are difficult to interpret as anything other than challenging the status quo. But I think there were a number of strategic miscalculations on both sides that make it somewhat difficult to divine intention from actions (i.e. did Germany believe they would trigger a huge war...well after 1870 and the relative peace of the 19th century, probably not). I think the mistake you are making (not one btw that is contained with realist theory) is assuming that agency is necessary...Germany did not need to "challenge", conflict was inevitable through changes in relative power...I wouldn't necessarily agree with that still but it is a fairly nuanced point. The stuff about the Thucydides Trap is also pretty questionable. Classical realist thought, of which Thucydides is part of, says that war between great powers is inevitable but this isn't really said explicitly in Thucydides (the first seed of these theories really come with Hobbes...I am guessing Hobbes' trap didn't pass muster with the editor). Allison cites statistics to justify the specific statement but these are pretty hopeless (similar to the issues with democratic peace theory...you can define things whatever way based on what conclusion you need). It is a great catchphrase and sounds very impressive but has always seemed rather devoid of content (Allison's views generally are). I am definitely sympathetic to realism but the whole "conflict is inevitable" stuff isn't really credible anymore.