I know that there was a shift in power but is there a reason as to why the Spanish and Portuguese were not able to maintain their power?
Well, i’m not sure as to 1450-1750, but originally, the Spanish and Portuguese had power due to their colonial expansion. With Portugal, their trading post empire allowed them to gain a lot of power and Spanish colonization of a lot of the Americas brought them power. But later, Britain had access to raw materials and resources so Industrialization took place and brought about their power. They started building railroads and using steamships so their expansion could be occurring more efficiently. They moved into Asia, Africa, and the Americas. France also gained territories in Africa and the Americas, whereas Spain concentrated mainly only in the Americas and Portugal did not go further in India beside their trading posts. Also with Napoleon’s conquest in the Americas, he got rid of the original Spanish ruler and causes more rebellion and unstability there. Hope this helped