The next year (56 B.C.) is signalised by several important speeches. Whatever we may think of his political conduct during this trying period, his professional activity was most remarkable. He defended L. Bestia [34] (who was accused of electoral corruption when candidate for the praetorship) but unsuccessfully; and also P. Sextius, [35] on a charge of bribery and illegal violence, in which he was supported by Hortensius. Soon after we find him in the country in correspondence with Lucceius, on the subject of the history of his consulship; but he soon returned to Rome and before the year ended delivered his fine speech on the consular provinces, [36] in which he opposed the curtailment of Caesar's command in Gaul; and also that on behalf of Coelius, [37] a lively and elegant oration which has been quoted to prove that Cicero was indifferent to purity of morals, because he palliates as an advocate and a friend the youthful indiscretions of his client. In 55 B.C. he pleaded the cause of Caninius Gallus, [38] in a successful speech now lost, and attacked the ex-consul Piso [39] (who had long roused his resentment) in terms of the most unmeasured and unworthy invective. Towards the close of the year he completed his great treatise, _De Oratore_, the most finished and faultless of all his compositions; and so active was his mind at this epoch, that he offered to write a treatise on Britain, if Quintus, who had been there with Caesar, would furnish him with the materials. His own poems, _de Consulatu_ and _de Temporibus suis_ had been completed before this, and, as we learn from the letters, were highly approved by Caesar. Next year (54 B.C.) he defended Plancius [40] and Scaurus, [41] the former of which orations is still extant; and later on, Rabirius Postumus, [42] who was accused, probably with justice, of extortion. This year had witnessed another change in Cicero's policy; he had transferred his allegiance from Pompey to Caesar. In 52 B.C. occurred the celebrated trial of Milo for the murder of Clodius, in which Cicero, who appeared for the defendant, was hampered by the presence of Pompey's armed retainers, and made but a poor speech; the magnificent and exhaustive oratorical display that we possess [43] having been written after Milo's condemnation and sent to him in his exile at Marseilles, where he received it with sarcastic praise. At the close of this year Cicero was appointed to the government of the province of Cilicia, where he conducted himself with an integrity and moderation little known to Roman pro-consuls, and returned in 50 B.C. scarcely richer than he had set out.