When did German failure become virtually certain in WW2?

[Georg Ebner]

Since ~1700.
The appearance of impressing continentalEuropeans like Prince EUGEN de Savoy, FREDERIC II, MIRABEAU, NAPOLEON, TALLEYRAND, METTERNICH, GARIBALDI, BISMARCK, WILLIAM II aso. overshadowed, that the decisive forces were increasingly England/US and Russia/SU. A development for not less than 300 years, culminating 1945ff. and ending only in the very recent past.

[Georg Ebner]

Since ~1700.
The appearance of impressing continentalEuropeans like Prince EUGEN de Savoy, FREDERIC II, MIRABEAU, NAPOLEON, TALLEYRAND, METTERNICH, GARIBALDI, BISMARCK, WILLIAM II aso. overshadowed, that the decisive forces were increasingly England/US and Russia/SU. A development for not less than 300 years, culminating 1945ff. and ending only in the very recent past.

Victory for England was only certain from 1815. Before then it was a tug of war between England, France, and Spain with no clear leading European power.

Even, if we saw it as the fights of soulless apeHerds, there would remain the fact, that EngLand ousted Spain&France in the colonies and erected its Empire - what do some victories or defeats on the continent count against that?!
Even more so, if we see it as the fights of human beings with ideas. (And even an amateur should be able to detect, that the antAgonism US-SU was based on distinct worldViews. Whose roots go back to 1700 [and earlier]).
The great P.HAZARD described well, how EngLand took over the leadership, first in philoSophy ("Locke-era") - MONTESQUIEU & VOLTAIRE learnt there -, then in manners (GAINSBOROUGH-aristoCrats!), finally in politics&economy. The XVIIIth was EngLand's siglo del oro.

[Georg Ebner]

Since ~1700.
The appearance of impressing continentalEuropeans like Prince EUGEN de Savoy, FREDERIC II, MIRABEAU, NAPOLEON, TALLEYRAND, METTERNICH, GARIBALDI, BISMARCK, WILLIAM II aso. overshadowed, that the decisive forces were increasingly England/US and Russia/SU. A development for not less than 300 years, culminating 1945ff. and ending only in the very recent past.

Victory for England was only certain from 1815. Before then it was a tug of war between England, France, and Spain with no clear leading European power.

Even, if we saw it as the fights of soulless apeHerds, there would remain the fact, that EngLand ousted Spain&France in the colonies and erected its Empire - what do some victories or defeats on the continent count against that?!
Even more so, if we see it as the fights of human beings with ideas. (And even an amateur should be able to detect, that the antAgonism US-SU was based on distinct worldViews. Whose roots go back to 1700 [and earlier]).
The great P.HAZARD described well, how EngLand took over the leadership, first in philoSophy ("Locke-era") - MONTESQUIEU & VOLTAIRE learnt there -, then in manners (GAINSBOROUGH-aristoCrats!), finally in politics&economy. The XVIIIth was EngLand's siglo del oro.

Spain’s holdings were much better and provided a higher ROI compared to the meager Caribbean island chains, the 13 colonies, and Canada. France had a much better geospatial position and prevented Hapsburg or English agendas all up till the late 1770s.

The notion that England provided good philosophical takes compared to the might and relevance of the Germanic—or even one man, Goethe— states or France is incorrect, and no stint in England by Voltaire is gonna change that

No idea, what "ROI" is supposed to mean - "revenues of island"?
Spain's siglo del oro ended roughly 1659, also politically. The French colonial experiments were always halfhearted and with the loss of NorthAmerica over (at least before taking IndoChina & Maghreb in the late XIXth).
You forgot to mention the decisive part of their Empire - India -, which was conquered in exactly those days.

KANT was freed by HUME, GOETHE&HERDER by SHAKESPEARE, german Romanticism by Scottish Ossianism.