Okay so the title is a bit clickbait. I think the spanish empire did succeed with a lot of thinks but it didnt survive as long as the British and french empire did.

After the 15-16th century Spain seems to lose all importance in global affairs.

For example when we talk about major European events after the Napoleonic wars* we only hear about the major players: United Kingdom, France, Germany, Russia, Prussia, Austria-Hungary, (I am sure im excluding some sorry if I am), but you never hear about Spain.

They seemed to not be involved in World War 1 or World War 2, which seems very odd to me when you consider they were like the first European Empire.

*And even when it comes to the Napoleonic wars it really feels like you can boil it down to France vs England and everyone else as helpless bystanders.

So the TL;DR is Why was the Spanish empire unable to succeed in maintaining relevance in the world after the Napoleonic wars

Also even in the 21st century Spain just doesn't feel like an important world power. I might be bias but when I think about Europe I start off with the United Kingdom then France then Germany and then maybe Spain. If you rate Spain higher consider if its because they are a actual regional power or if it is because of recent events such as Catalonia's referendum and the terrorist attack that happened there about 1 a year or 2 ago.

Before I get raged at by anyone I know i am oversimplifying and getting things wrong, I really do love history but I am not a historian by any means and I forget small details a lot, so sorry if i missed or messed up something.