The magistrature of tribune of the people (tribunus plebis) was established in 494 BC, about fifteen years after the foundation of the Roman Republic in 509. The plebeians of Rome seceded as a group -- that is, they left the city entirely -- until the patricians agreed to the establishment of an office that would have sacrosanctity (sacrosanctitas) -- that is, the right to be legally protected from any physical harm -- and the right of help (ius auxiliandi) -- that is, the right to rescue any plebeian from the hands of a patrician magistrate. Later, the tribunes acquired a far more formidable power, the right of intercession (ius intercessio) -- that is, the right to veto any act or proposal of any magistrate, including another tribune of the people ("veto" is Latin for "I forbid"). The tribune also had the power to exercise capital punishment against any person who interfered in the performance of his duties (the favourite threat of the tribune was therefore to have someone thrown from the Tarpeian Rock). The tribune's sacrosanctity was enforced by a solemn pledge of the plebeians to kill any person who harmed a tribune during his term of office.