Through an aristocratic revolution the kingdom was overthrown, and the king gave place to two annually elected magistrates, called later consuls, who had the right of veto on each other’s actions. The consuls were chosen from the ranks of the patricians, or ruling families, and at the end of a year became patricians again. They must therefore have been largely governed in their action by class prejudice. Consequently the position of the classes which lacked political privileges became intolerable. Another element in the situation aggravated the difficulty. Being located in the centre of Italy and on a navigable river, and being far enough from the mouth of the river to be safe from pirates, Rome grew rapidly, and the coming of a large number of immigrants to the city had a profound effect on its political history. The newcomers did not enjoy the same civil and political rights as the members of the original clans, and they were at an economic and social disadvantage. The constitutional history of Rome for several centuries centres about the struggle of these people and of the other members of the lower classes to remove the limitations which were put on their rights in these four respects. The natural method of guarding the civil rights of the commons against the arbitrary action of the patrician consul was to limit his powers by law. But the Romans did not adopt this method. They chose class representatives, called tribunes, who were authorized to intervene in person when a plebeian was being treated unjustly and prevent the chief magistrate from carrying out his purpose. It is characteristic of the Roman, as we shall see in other cases, to take this concrete, personal way of bringing about a constitutional reform. The plebeians were at a disadvantage also, because they were kept ignorant of legal procedure and could not maintain their rights before a magistrate. The details of the law, or the accepted custom, were known only to the patrician priests and were handed down by word of mouth from one generation to another. About the middle of the fifth century, after a long struggle, this law was codified and was engraved on twelve bronze tablets, and the tablets were hung up in the Forum where they might be read by any one. These Twelve Tables[2] were regarded by the Romans as the basis of their civil liberty, and may well be placed by the side of the Mosaic Code, the laws of Hammurabi, the Gortynian Code, and Magna Charta. As we shall see later, they contained no formulation of general rights, but stated clearly and minutely the procedure to be followed in civil and criminal actions. If we may accept tradition, both these battles with the patricians were won by the very modern method of Direct Action.