(Not to be confused with Taiwan's February 28 Incident)
The February 26 Incident (二・二六事件 Ni-niroku jiken in Japanese) took place in 1936. 1,400 junior military officers took up arms in Tokyo, occupying the Diet, army ministry, and police headquarters. Three cabinet members were killed, including finance minister Takahashi Korekiyo. A band of officers stormed the Kantei (the prime minister's residence) and attempted to kill Prime Minister Okada Keisuke, Admiral Suzuki Kantaro, and Prince Saionji Kimmochi. Most of the city ended up effectively under rebel control.
The rebels were fighting in the name of the emperor against what they saw as a pro-industry, overly political government that needed to pay more attention to conquering Asia. Hirohito responded by ordering the Army and Navy to suppress the revolt. On the 29th, both services reported that they had captured all the rebels, and either executed them or demanded that they commit ritual suicide. Martial law was imposed until July, and Okada was forced to resign in March, making way for a new premier, Hirota Koki (who ended up signing Japan's alliance with Germany).
The story behind the 2-26 Incident is as controversial in Japan as the Kennedy assassination is in the United States. Although there is no conclusive evidence to support their position, many believe that Hirohito's younger brother, Prince Chichibu Yasuhito, was behind the revolt. Some conspiracy theorists have gone as far as to say that Hirohito and his cohorts staged the rebellion to make it possible to justify stronger internal security measures.
Whatever the motive behind it was, 2-26 wiped out the pro-peace factions in Japan and placed the entire country on a solid militarist footing, an important step in the escalation of the Second Sino-Japanese War toward Shanghai and the Rape of Nanking.