Major difficulty: the question implies an united, or reunited Germany and in OTL 19th C. Germany was largely reunited *against* France: the German 'national' sentiment was rooted in the memories of the Napoleonic wars, re Schenkendorf's Wenn alle untreu werden &c., for the Prussians 1870 was the revenge of Iena. So 'no Franco-Prussian War' seems a little too late. Anglophobia was still strong in France, revived by the colonial competition, but because of the family ties between Queen Victoria and the Kaiser an anti-British Franco-German alliance is less likely than the opposite.
Slightly earlier? Suppose Napoleon calmed down after his wedding with Marie-Louise and get rid of Spain by offering the crown to come back to a (minor) Habsburg. No disastrous Russian campaign, a long-lasting empire with the half-Austrian 'Eaglet' succeeding his father, Prussia a minor state. Could Germany unify around Austria, despite this last being tangled in a multi-cultural, multi-ethnical political entity? But the key factor is the attitude of Great-Britain: Napoleon's adventurous wars aimed at enforcing the Continental Blocus in order to compel Great Britain to leave Continental Europe alone, while the British policy was to 'divide to rule'.
Something along this lines could be set some 50 years earlier, had the French diplomacy realized sooner than the 'German threat' was no longer the Habsburgs but Prussia, and France not entered the War of Austrian Succession -or fought on the Austrian side as in the SYW. Louis XV's son rather than great-son could have married an Austrian princess.
(Btw how do you define a 'WW'? Some argue that the War of Austrian Succession was the 1st WW; but since Germany was not unified yet, the WAS is anyway irrelevant here).
The earliest relevant POD would have Louis the Pious with only two surviving sons, no Middle Frankish Kingdom, the Alps and the Rhine set as natural border between the Roman-speaking Western Franks and the Old High German-speaking Eastern Franks with the Pope's blessing.