The Saint Valentine's Day Massacre is the name given to the 1929 murder of six mob associates and a mechanic of the North Side Irish gang led by Bugs Moran during the Prohibition Era. It resulted from the struggle — between the Irish American gang and the South Side Italian gang led by Al Capone. Al Capone reveled in the fact that he thought he had killed Bugs Moran. However, he missed him by only a few short minutes.

More Info: en.wikipedia.org