 When the Chilean government ordered that vessels supplying or communicating with the Spanish fleet should not be allowed to enter Chilean ports, Méndez Núñez's first target became the most important and undefended Chilean city of Valparaíso.Efforts to mediate were initially steered by European diplomats whose countrymen were most affected by the initial blockade of Chilean ports and by the threat of bombardment.High-level contacts took place intensively in late 1865 and early 1866 between London, Paris and Madrid.