The initial concept for the invasion of Castro's Cuba was for America to train and support a series of guerrilla units comprised of Cuban exiles. These guerrilla units were to be landed at various strategic locations throughout Cuba. The positions were chosen for their ease of conquest and the probability of these groups being joined with anti-Castro groups native to those areas. The plan was changed when word was received that the Soviet Union had supplied Castro's army with a wealth of military equipment, including tanks and an array of support and attack aircraft.
The revised plan was that a much larger brigade of Cuban exiles would land on Cuba at Trinidad-Casilda. Prior to the landing, there would be three days of bombings to be carried out by a fleet of old WWII-era B-26 bombers flown from bases in Nicaragua by Cuban pilots. These bombings were to strike at Castro's air bases, destroying the majority, if not all, of the Cuban air force. The brigade would then land and would continue to receive air support from these bombers. The brigade would then establish themselves and, if everything went well, would unite with the native guerillas which were already creating problems for Castro.
That was the intended plan.
Constant fear of being connected with the insurrection on the part of the United States Government led to some further revisements that would be the undoing of the entire operation.
First, the planned site of the landing, Trinidad-Casilda, was seen by the Americans as being too obvious a place, and too "American" in style. The alternate location of the Bay of Pigs and adjacent Girón Beach was chosen by the American military leaders, even though it was strategically inferior for an armed landing than Trinidad-Casilda.
Second, on April 15th, 1961, (when the bombings were to begin), the airstrikes began on several airbases. The damage inflicted was minimal due to the fact that last minute plans cut the number of bombers used in half (So as to make it look more like an armed uprising of Castro's own forces). Furthermore, due to the scandal generated, the two remaining planned air raids, were canceled.
On April 17th, the Assault Brigade 2506 was sent into the Bay of Pigs to begin the land invasion. They were not able to count on the vital aerial supremacy, they were inferior numerically, and the landing was not carried out in Trinidad (where the brigade was more likely to receive help from the population which was considered to be opposed to the regime and known to have a better coastline and with the Escambray mountains nearby to where the Brigade could retreat). There were other disadvantages at the start of the operation: a swampy area with a coralline coast and a nocturnal landing. This was unprecedented for conventional amphibious operations planned by the American military.
Castro's jet fighters destroyed the slower, less agile B-26 bombers. In turn, the highest casualties were among the Brigade's pilots. Also destroyed by the air force were two supply ships, the Houston and the Rio Escondido, which were both full of supplies.
Despite all of these shortcomings, and the eventual losing outcome for the Assault Brigade 2506, the men fought bravely and effectively. As did the soldiers on Castro's side, who suffered a greater number of casualties.
To this day, the Bay of Pigs situation remains an example of one of the world's worst military blunders, a tragedy in history, and a blemish on U.S.-Cuban relations.