Besides the conspiracy of Catiline and the Jugurthine War, which have been preserved entire, and from which our estimate of the merits of Sallust must be chiefly formed, he was author of a civil and military history of the republic, in five books, entitled, _Historia rerum in Republica Romana Gestarum_. This work, inscribed to Lucullus, the son of the celebrated commander of that name, was the mature fruit of the genius of Sallust, having been the last history he composed. It included, properly speaking, only a period of thirteen years,--extending from the resignation of the dictatorship by Sylla, till the promulgation of the Manilian law, by which Pompey was invested with authority equal to that which Sylla had relinquished, and obtained, with unlimited power in the east, the command of the army destined to act against Mithridates. This period, though short, comprehends some of the most interesting and luminous points which appear in the Roman Annals. During this interval, and almost at the same moment, the republic was attacked in the east by the most powerful and enterprizing of the monarchs with whom it had yet waged war; in the west, by one of the most skilful of its own generals; and in the bosom of Italy, by its gladiators and slaves. This work also was introduced by two discourses--the one presenting a picture of the government and manners of the Romans, from the origin of their city to the commencement of the civil wars, the other containing a general view of the dissensions of Marius and Sylla; so that the whole book may be considered as connecting the termination of the Jugurthine war, and the breaking out of Catiline's conspiracy. The loss of this valuable production is the more to be regretted, as all the accounts of Roman history which have been written, are defective during the interesting period it comprehended. Nearly 700 fragments belonging to it have been amassed, from scholiasts and grammarians, by De Brosses, the French translator of Sallust; but they are so short and unconnected, that they merely serve as land-marks, from which we may conjecture what subjects were treated of, and what events were recorded. The only parts of the history which have been preserved in any degree entire, are four orations and two letters. Pomponius Lætus discovered the orations in a MS. of the Vatican, containing a collection of speeches from Roman history. The first is an oration pronounced against Sylla by the turbulent Marcus Æmilius Lepidus; who, (as is well known,) being desirous, at the expiration of his year, to be appointed a second time Consul, excited, for that purpose, a civil war, and rendered himself master of a great part of Italy. His speech which was preparatory to these designs, was delivered after Sylla had abdicated the dictatorship, but was still supposed to retain great influence at Rome. He is accordingly treated as being still the tyrant of the state; and the people are exhorted to throw off the yoke completely, and to follow the speaker to the bold assertion of their liberties. The second oration, which is that of Lucius Philippus, is an invective against the treasonable attempt of Lepidus, and was calculated to rouse the people from the apathy with which they beheld proceedings that were likely to terminate in the total subversion of the government. The third harangue was delivered by the Tribune Licinius: It was an effort of that demagogue to depress the patrician, and raise the tribunitial power, for which purpose he alternately flatters the people, and reviles the Senate. The oration of Marcus Cotta is unquestionably a fine one. He addressed it to the people, during the period of his Consulship, in order to calm their minds, and allay their resentment at the bad success of public affairs, which, without any blame on his part, had lately, in many respects, been conducted to an unprosperous issue. Of the two letters which are extant, the one is from Pompey to the Senate, complaining, in very strong terms, of the deficiency in the supplies for the army which he commanded in Spain against Sertorius; the other is feigned to be addressed from Mithridates to Arsaces, King of Parthia, and to be written when the affairs of the former monarch were proceeding unsuccessfully. It exhorts him, nevertheless, with great eloquence and power of argument, to join him in an alliance against the Romans: for this purpose, it places in a strong point of view their unprincipled policy, and ambitious desire of universal empire--all which could not, without this device of an imaginary letter by a foe, have been so well urged by a national historian.