Portugal absolutely collapsed, due to the 1755 Lisbon earthquake. Voltaire wrote about this[1]. The Portuguese Empire couldn't cope with the near total destruction of their capital, and never recovered. During the Napoleonic wars, the emperial court moved to Brazil and, basically, hid. They were a shadow of themselves.

The United Kingdom, similarly, collapsed, under the weight of two world wars. Europe as a whole was devastated, and the whole world started to coalesce around the only remaining global powers.

[1] https://en.m.wikipedia.org/wiki/Po%C3%A8me_sur_le_d%C3%A9sas...