Mexico had suspended interest payments on the nation's giant foreign debt in July 1861. The main European debtors, Britain, France, and Spain, signed a convention in London for an occupation of Mexican customs houses, beginning with Vera Cruz, to force continued payments.  A combined fleet sailed in December 1861. When the agreement broke down, France took the opportunity for a full scale intervention in Mexico in early 1862.  (By John Osborne)   
Source Citation
Brian R. Hamnett, A Concise History of Mexico (New York: Cambridge University Press, 1999), 163-164. 
    Date Certainty
    Exact
    Type
    US/the World

    How to Cite This Page: "In London, Britain, France, and Spain agree to a military intervention in Mexico to force payment of debts," House Divided: The Civil War Research Engine at Dickinson College, https://hddev.housedivided.dickinson.edu/node/38530.