The French engineer, physicist, Nobel laureate, and the first person to discover evidence of radioactivity, Henri Becquerel died there in 1908.

[5] During World War II, Le Croisic was home to a radar station for the Wehrmacht following the Fall of France and construction of the U-boat pens at Saint-Nazaire, in order to protect the Loire estuary from Allied attacks due to the Normandie dry dock at Saint-Nazaire that could be used to repair the large Kriegsmarine battleships such as the Bismarck and its sister ship, Tirpitz.

However, in the March 1942 St Nazaire Raid, a British Commando team on the obsolete HMS Campbeltown and several motor launch boats were able to slip by the Le Croisic radar station and ram Campbeltown into the Normandie dry dock gate, before sabotaging other vital parts to the dry dock.

Delayed action explosives on Campbeltown went off several hours after the night raid, destroying the dry dock gate and putting it out of commission until long after France was liberated and Nazi Germany had surrendered to the Allied Powers.

[6] In a medieval French legend recounted during the funeral of Anne of Brittany in 1514, Le Croisic was the scene of a story which explained the origin of the use of ermine in heraldry.