 Collatinus, together with his father-in-law, Spurius Lucretius Tricipitinus, and his companions, Lucius Junius Brutus and Publius Valerius, swore an oath to expel the king and his family from Rome.As Tribune of the Celeres, Brutus was head of the king's personal bodyguard, and entitled to summon the Roman comitia.This he did, and by recounting the various grievances of the people, the king's abuses of power, and by inflaming public sentiment with the tale of the rape of Lucretia, Brutus persuaded the comitia to revoke the king's imperium and send him into exile.