Publius Rutilius Rufus (c.158 BC – after 78 BC, junior consul in 105) was an honorable Roman statesman, orator, stoic, and historian, and most likely great-uncle of Gaius Julius Caesar.
Theodor Mommsen writes in Book 57 of his History of Rome:
In this respect [Quintus Metellus] was so far free from the prejudices of his order that he selected as his lieutenants not men of rank, but the excellent officer Publius Rutilius Rufus, who was esteemed in military circles for his exemplary discipline and as the author of an altered and improved system of drill…
Collision Between the Senate and Equites in the Administration of the Provinces:
Everything depended on recovering the nomination of the jurymen. The administration of the provinces--the chief foundation of the senatorial government--had become dependent on the jury courts, more particularly on the commission regarding exactions, to such a degree that the governor of a province seemed to administer it no longer for the senate, but for the order of capitalists and merchants. Ready as the moneyed aristocracy always was to meet the views of the government when measures against the democrats were in question, it sternly resented every attempt to restrict it in this its well-acquired right of unlimited sway in the provinces. Several such attempts were now made; the governing aristocracy began again to come to itself, and its very best men reckoned themselves bound, at least for their own part, to oppose the dreadful maladministration in the provinces. The most resolute in this respect was Quintus Mucius Scaevola, like his father Publius -pontifex maximus- and in 659 consul, the foremost jurist and one of the most excellent men of his time. As praetorian governor (about 656) of Asia, the richest and worst-abused of all the provinces, he--in concert with his older friend, distinguished as an officer, jurist, and historian, the consular Publius Rutilius Rufus--set a severe and deterring example. Without making any distinction between Italians and provincials, noble and ignoble, he took up every complaint, and not only compelled the Roman merchants and state-lessees to give full pecuniary compensation for proven injuries, but, when some of their most important and most unscrupulous agents were found guilty of crimes deserving death, deaf to all offers of bribery he ordered them to be duly crucified. The senate approved his conduct, and even made it an instruction afterwards to the governors of Asia that they should take as their model the principles of Scaevola's administration; but the equites, although they did not venture to meddle with that highly aristocratic and influential statesman himself, brought to trial his associates and ultimately (about 662) even the most considerable of them, his legate Publius Rufus, who was defended only by his merits and recognized integrity, not by family connection. The charge that such a man had allowed himself to perpetrate exactions in Asia, almost broke down under its own absurdity and under the infamy of the accuser, one Apicius; yet the welcome opportunity of humbling the consular was not allowed to pass, and, when the latter, disdaining false rhetoric, mourning robes, and tears, defended himself briefly, simply, and to the point, and proudly refused the homage which the sovereign capitalists desired, he was actually condemned, and his moderate property was confiscated to satisfy fictitious claims for compensation. The condemned resorted to the province which he was alleged to have plundered, and there, welcomed by all the communities with honorary deputations, and praised and beloved during his lifetime, he spent in literary leisure his remaining days.
Rutilius' conviction in 92 marked the bankruptcy of the equestrian courts; his nephew, the tribune of the plebs of 91 Marcus Livius Drusus, removed the jury courts from the jurisdiction of the equites.
Aside from the drill manual, Rutilius is known to have written his memoirs in exile – much used by later historians, among them most likely Sallust – but no longer extant. He also wrote on the Ius Civile.
In McCullough's novels, beginning with First Man in Rome, he is an inveterate gossip and letter writer.
Ernst Badian has written an excellent book on tax farmers: Publicans and Sinners: Private Enterprise in the Service of the Roman Republic with a Critical Bibliography. For German speakers, the German version, Zöllner und Sünder: Unternehmen im Dienst der römischen Republik, ISBN 3534131436, translation supervised by the author, can be found on the used book market in the US, and at amazon.de.