On the morning of 17th April, 1961, a force of Cuban counter-revolutionary exiles, known as Brigade 2506, landed at the Bay of Pigs in an attempt to overthrow Fidel Castro’s regime. The attack was carried out with the support of the United States of America: the plan having been drafted by the C.I.A. while Dwight D. Eisenhower was still President, but was carried out during John F. Kennedy’s presidency. Kennedy required the original plan to be scaled back, so that it the attack would look less like a U.S. military operation and more like an operation that the exiles could plausibly carry out.
Following an attack by light bombers of the exile air force, launched from Nicaragua on Cuban airfields, the main assault on the Bay of Pigs began. The failure of the air attack to destroy the Cuban air force resulted in the surviving planes wreaking havoc on the counter-revolutionary invasion force and their air support. Fighting continued, as a 20,000 strong Cuban force repulsed the invading troops, leading to the collapse of the attack on 19th April.
The failed invasion caused a rapid deterioration of diplomatic relations between the U.S. and Cuban governments, which worsened during the Cuban Missile Crisis of the following year, and have improved little in successive decades.
To find out more about the Bay of Pigs Invasion, read the original New York Times report on the attack, and the article about the invasion on the JFK Library and Museum web site.