The Paris Compressed-Air Power Network (2018)

>Impressive! At the time, France was the world's leading power and accomplished great things (the tallest building in the world, advances in all scientific fields, etc.).

It was pretty clear to everyone at that time that France is being eclipsed by the rising Germany next door. They got soundly defeated in 1870 and demographics coupled with economic growth rates were only going to make that disparity greater (and did).

https://en.wikipedia.org/wiki/Great_power Lists Great Britain as the leading power of the time, and I would agree. I think France was leading earlier, when Napoleon was in power.