La Belle Époque was a period of Western European history. It is conventionally dated from the end of the Franco-Prussian War in 1871 to the outbreak of World War I in around 1914.
We in USica barely know anything about this time period, even in our own history. American history usually goes
Mayans & Aztecs in 3,000 BC or something > Lief Erikson > Christopher Columbus > Pilgrims, Squanto, Pocahontas, and Turkeygiving > Puritans > George Washington and his droogs create America in 1776 > Louisiana Purchase > Andrew Jackson > War Of Northern Aggression, known by anti-state's rights revisionists as the 'Civil War' > Lincoln Dies > Cowboys 'n Indians > Teddy Roosevelt > World War I > Jazz 'n Cars > Great Depression, New Deal, and Dust Bowl > World War II: Ultimate Valor > Cold War > Vietnam War with hippies and rock music > Disco > Reagan > We Won The Cold War > 9/11 > Obama
There you go, that's what the average American knows of history. Notice how I didn't go into detail. That wasn't just because I was trying to get to the point, but also because that's legitimately how much the average USican knows of history.
There are wide swaths of history that average USicans know absolutely nothing about. The Belle Époque is one of those times. Bring up the 1870's to 1914, and the only thing the average USican can guess about those years is that we got Teddy Roosevelt and that there were a lot of Cowboys shooting Indians. How we got to World War I, we don't exactly know. There were alliances, right? And Germany was evil and something... Were they friends with Japan and Italy yet?
In fact, that time period from 1871 to 1914 is unbelievably complex, and you can definitely see fate planting the seeds of our modern world. It was a Post-Napoleonic, Post-1848 era.
It may be that geopolitics prior to 1914 are rather alien to us that the period doesn't resonate with people well. This era was a time of Old meeting New, where you had powerful royal families ruling alongside powerful industrial capitalists, something we don't see today since the industrial capitalists ultimately won out.
Things were optimistic back then. As optimistic as they are now, to be precise, though without the caveat of there being digital technology.
However, if you were interested in technology, there might as well have been supercomputers during that era. It was during this time that we saw the development of things like modern automobiles and aeroplanes. The sci-tech world was on fire, and we were so sure that human civilization was living in a golden age. We were sure of how good things were and believed things would get even better.
Of course, we were innocent. We were developing mechanized, industrial armies of death that would prove capable of mowing down millions of men in hours, but we had never seen them in action before.
At least, those who would eventually fight had never seen them in action. European generals failed to learn from the US civil war because they thought it was simply an unusually violent affair that had no bearings on European warfare. Even after the Russo-Japanese War saw some of the same things happen— machine guns, trench warfare, and the like— they refused to learn.
So in the meantime, we got a chance to relax. There was colonialism and imperialism that Europe profited from, but that didn't help them stay above the US.
It was during this period that the US overtook the UK as being the world's largest economy, for example. And this was also during the middle of the Second Industrial Revolution.
Things had never been better, despite things like the Great Panic of 1894.
One of the things I love the most from this era is the artwork. This was right at the very beginning of our ugly-ass modern art, as well as towards the very end of the classical, traditional age of art. The rich were partying excessively, and the poor were working excessively.
Intellectuals were flourishing, and so many things we take for granted (brand name foods, brands, banks, companies, etc.) were formed.
There were few big wars during this time, and geopolitics seemed stable.
But, of course, the people of this era did not have things such as artificial intelligence to aid in their understanding (and misunderstanding) of their own increasingly complex society, and we were too unused to so many developments (such as the development of trusts and unregulated banking) to know exactly what to do. We viewed the world as our plaything, and the future as our right.
It should be noted that this era is probably the closest to steampunk we've ever gotten as a species.
It's also an era that wasn't as rosy as its name suggests. After all, it's during this time that things like ultranationalism, racial eugenics, and excessive pseudo-science entered the mainstream.