Ronin's blog: "Ronin"

A group of samurai who were left leaderless (became ronin) after their master was forced to commit seppuku (ritual suicide) for assaulting a court official named Kira Yoshinaka. The ronin avenged their master's honor after patiently waiting and planning for over a year to kill Kira. Early in the morning of December 14 1702, in a driving wind during a heavy fall of snow, Ōishi and the ronin attacked Kira Yoshinaka's mansion in Edo. According to a carefully laid-out plan, they split up into two groups and attacked, armed with swords and bows. A drum would sound the simultaneous attack, and a whistle would signal that Kira was dead. A few days following this event 46 Ronin handed themselves in. As expected, the ronin were sentenced to death. The Shogun ordered them to honorably commit seppuku (ritual suicide), instead of having them executed as criminals. The forty-six ronin did so on February 4, 1703.
Tale Of The Forty-Seven Ronin by ~ChrisRawlins on deviantART