The significance of the Bay of Pigs invasion in U.S. history lies in its failure and its impact on U.S.-Cuba relations during the Cold War. In April 1961, an unsuccessful CIA-backed invasion was launched by Cuban exiles to overthrow Fidel Castro's communist government. The invasion quickly faltered, resulting in the capture of many exiles and a public relations disaster for the U.S. government. This event intensified Cold War tensions, solidified Castro's power, and led to increased Soviet support for Cuba, ultimately contributing to events like the Cuban Missile Crisis.