The events of D-Day on June 6, 1944, were the result of years of careful planning, deception, good luck, and setbacks. As we near another D-Day anniversary, it is important to understand what transpired before the massive invasion of Normandy. Here are a few highlights that you may have never heard about:

The Tragedy and Massacre at Slapton Sands

In April 1944, in Slapton Sands, Devon, Allied troops conducted a large-scale mock invasion to prepare for the inevitable invasion of Normandy. The training operation was dubbed Exercise Tiger and involved over 30,000 men.

On April 27, a large Allied beach landing was planned. General Eisenhower had ordered British battleships to shell the beach with live rounds, right up until the landing craft landed, in an attempt to prepare soldiers for what they would encounter in Normandy. At the last minute, the invasion was pushed back an hour. But of course, not all of the invasion units learned of this schedule change, resulting in some Higgins boats landing on the beach early and being hit by friendly fire.

The next piece of this story is made up of rumors and cover-ups and has never been confirmed or verified by the United States Government. According to eye-witness accounts and documented stories, the roleplaying defenders on the beach, who were also Allied soldiers, used live ammunition during the training exercise.

Some say that Eisenhower had ordered the defenders to have live ammunition and to shoot over the soldiers’ heads. Others claim that the roleplayers were supposed to be given dummy rounds, but accidentally were supplied with live rounds. The story goes that the soldiers were mowed down on the beach, resulting in the death of somewhere between 300 to 450 soldiers. Yet, as aforementioned, this story is strictly hear-say and has never been officially confirmed.

Unfortunately, things were to only get worse for the Allied mock invasion force.

The night after this fateful invasion, German E-Boats were cruising off the Devon coast and came across a group of Tank Landing Ships (LSTs). These LSTs were a part of an Allied convoy headed to Slapton Sands from Plymouth. They were loaded with soldiers from the U.S. Army’s VII Corps, who were to serve as the second wave of the practice invasion, the next morning. HMS Azalea, a Royal Navy Corvette, was the only escort of the flotilla. The Azalea had identified and reported the E-Boats, but due to communication failures, the rest of the convoy were never made aware of the impending threat.