In December 1825 a group of army officers, who became known as the Decembrists, led soldiers in a revolt which took place on St Petersburg's Senatskaya Ploschad (Senate Square) against the ascension of Emperor Nicholas I and demanding a constitution and the abolishment of autocracy. The uprising was unsuccessful and ended in bloodshed. In 1926 five of the leaders (Pavel Pestel, Kondraty Ryleev, Sergey Kakhovsky, Sergey Muraviev-Apostol and Mikhail Bestuzhev-Ryumin) were publically hanged (on the second attempt as the ropes broke on the first) to the east of the crownwork of the Peter and Paul Fortress. In 1976, on the 150th anniversary of the uprising, an obelisk was unveiled in honour of these noblemen who lost their lives in their struggle against autocracy.