Here are some of my suggestions fo POD and backstory:
The most important changes you need are 1) a different German unification that follows the (very)Great Germany solution, with nobody interfering, and 2) a British empire that is for some reason hostile towards the US and willing to make allies on the European continent. Everything else can fall into place after that.
I think you can get this with a POD in the 1860's (earlier is maybe better, but then you also risk bigger complications with the butterfly effect.)
Let's say for exemple that in the 1860's the British (and the French) get into a war with the US, maybe over the CSA, maybe over Mexico, and they somehow loose...badly. This defeat is very traumatic for the British, so they decide to abandon their policy of isolation and seek strong allies for a "revanche" against the US. They sigh a formal alliance with the Prussians and give them free hand in Germany. As a result the Habsburg empire is completely annexed by Prussia (here something has to change about Bismark too). Britain also becomes more militaristic. France does not intervene because it is allso weakened by war, and because of British pressure. It does however feel threatened by Germany and embittered against Britain, so it forms the alliance with Russia as in OTL. Later this is extended to a triple entente with the US (most likely brokered by Russia).
Cue alternate ww1...
The most important changes you need are 1) a different German unification that follows the (very)Great Germany solution, with nobody interfering, and 2) a British empire that is for some reason hostile towards the US and willing to make allies on the European continent. Everything else can fall into place after that.
I think you can get this with a POD in the 1860's (earlier is maybe better, but then you also risk bigger complications with the butterfly effect.)
Let's say for exemple that in the 1860's the British (and the French) get into a war with the US, maybe over the CSA, maybe over Mexico, and they somehow loose...badly. This defeat is very traumatic for the British, so they decide to abandon their policy of isolation and seek strong allies for a "revanche" against the US. They sigh a formal alliance with the Prussians and give them free hand in Germany. As a result the Habsburg empire is completely annexed by Prussia (here something has to change about Bismark too). Britain also becomes more militaristic. France does not intervene because it is allso weakened by war, and because of British pressure. It does however feel threatened by Germany and embittered against Britain, so it forms the alliance with Russia as in OTL. Later this is extended to a triple entente with the US (most likely brokered by Russia).
Cue alternate ww1...