April 28, 1965 — US Marines occupy Santo Domingo

The Dominican Civil War was not even a week old before Lyndon Johnson decided that it posed a threat to US interests (to be fair to Johnson, the Cuban Missile Crisis was only three years earlier, and Johnson was worried that ‘another Cuba’ was about to form). The US Marines landed near Santo Domingo (the capital of the Dominican Republic) on April 28, and had captured the city within a day or so – the Constitutionalist forces surrendered the city on the following day.

The Dominican Civil War dragged on until September, and American forces remained in occupation until July of the following year, when somebody the US liked could be elected.

Honduran soldiers, first troops of Inter-American peace force, arrive to assume peace-keeping duties and to render emerg - NARA - 541976.tif
By Unknown or not provided – U.S. National Archives and Records Administration, Public Domain, Link

As mentioned in:

Send The Marines — Tom Lehrer