American newspapers of the 1780s argued politics under Roman names, and in the autumn of 1787 the New York papers were full of them. Writers signing as Cato and Brutus attacked the Constitution drafted that summer in Philadelphia. The reply that began on 27 October signed itself Publius, after Publius Valerius Poplicola, who by Roman tradition helped drive out the last king in 509 BCE and served as one of the republic's first consuls. Tradition remembered him as a founder who refused to become a king: when rumour read the house he was building on the Velian hill in Rome as proof that he meant to rule alone, he had it pulled down in a single night, and he gave citizens the right to appeal against a magistrate's sentence. The literary historian Albert Furtwangler ranks the name above those of the Caesars, Catos and Brutuses who signed the other newspaper essays.
Alexander Hamilton, a New York lawyer who had sat in the Philadelphia convention, ran the series. He had signed as Publius once before, in three letters of 1778 exposing Samuel Chase, a Maryland delegate to Congress, for trying to corner the flour market with what he learned there. Hamilton brought in John Jay, the Confederation's secretary for foreign affairs, and James Madison, a Virginian then in New York as a delegate to Congress; Gouverneur Morris, a fellow delegate at Philadelphia, was asked too, and declined. Jay fell ill after the fifth paper and wrote only one more, leaving two men to write as one at a pace set by the printer. Madison later recalled that the first part of a paper was often being set in type while the rest was still being written. At first he and Hamilton showed each other their drafts, then stopped, partly for lack of time and partly, Madison explained, because neither wanted to approve every doctrine of the other when their political theories were known to differ.
What held them together was the question Publius put in his first paper: whether a people can set up good government by reflection and choice, or must always take its constitutions from accident and force. His answer ran against the opposition's central fear. A national government strong enough to hold thirteen states in one union, he argued, was not the enemy of liberty but its protection, provided it was built so that each branch had both the means and the motive to resist the others. That is the claim Publius is remembered for, and American courts still cite him when they ask what the drafters of the Constitution meant.
The secret was kept loosely. In private letters a New Hampshire doctor reported that readers there took Publius to be Hamilton, while a New York merchant gave Madison the principal hand. Opponents attacked the persona instead of the men: the Northern Centinel, a paper in Lansingburgh, New York, pictured Publius as a man who cared only for present gain. Madison's last paper appeared on 1 March 1788 and he left New York days later, so Hamilton finished alone. In the last paper, printed on 28 May in the second volume of the collected edition, The Federalist, Publius admitted that he had often felt a struggle between strong feeling and restraint.
The single voice did not outlast the occasion. In 1793 Hamilton, writing as Pacificus, defended President Washington's proclamation of neutrality and a broad presidential power over foreign affairs, and Madison, pressed by Thomas Jefferson, answered him as Helvidius, arguing that Congress must share that power. The quarrel later reached the book itself. Shortly before his death in 1804 Hamilton left a list claiming sixty-three of the eighty-five papers, three of them shared with Madison, and Madison's list of 1818 claimed twenty-nine. The historian Douglass Adair assigned the twelve disputed papers to Madison in 1944, and a statistical study in 1964 agreed, though some scholars still hold that a few of them were written jointly.