February 14 - 1929 - The St. Valentine's Day Massacre
The St. Valentine's Day Massacre might be the most famous gangland killing in American history, and it might have become that as soon as it happened. The bare facts are that four associates of Al Capone entered a garage, with two posing as police officers, and killed seven associates of Bugs Moran and his North Side Gang. This made Capone's organization the premier criminal group in Chicago, which meant that Capone was in charge of most of the bootlegging and rackets. While Capone achieved his goal of taking out a rival gang, he also became the target of law enforcement and authorities, due to the brazen and overwhelming violence of the St. Valentine's Day Massacre. The actual killers, who were mostly hired guns, would be tracked down over the years, pointing the finger back at Capone and his outfit. So the St. Valentine's Day Massacre was both the signature event of Chicago gangs of the 1920s and the moment when the public perception turned on them.