Britain joined France and Spain in the 1861 expedition to pressure Mexico over unpaid debts.
The three powers agreed to cooperate after Mexico suspended payments on foreign obligations during a financial crisis. Their forces occupied Veracruz in early 1862, intending to negotiate repayment rather than immediately overthrow Mexico’s government.
Britain participated in the initial expedition but did not support France’s wider plan to establish a monarchy in Mexico. After diplomatic discussions and the Convention of Soledad, British forces withdrew. Spain also left, while France continued its military campaign.
The British role is often missed because Cinco de Mayo focuses on the French attack at Puebla. Britain was part of the intervention’s opening phase, but it was not the country defeated by Mexico at the 1862 battle.