Napoleon I, of the Empire of France, orders Ferdinand VII, of Spain, under threat of a firing squad, to abdicate—both for himself and his father, Charles IV. Napoleon then places his brother Joseph on the Spanish throne.
NOTE: This touches off the Peninsular War.
[added 12/27/2024]
Subsequent Events:
References:
Winston Churchill, A History of the English-Speaking Peoples, four volumes. (London: Cassell, 1956-58), 3:312.
Ferdinand VII of Spain – Wikipedia
en.wikipedia.org/wiki/Ferdinand_VII_of_Spain