Inde cum se in Italiam recepisset, duabus Hispaniis et Gallia Transalpina praesidiis ac navibus confirmata, missis item in oram Illyrici maris et in Achaiam omnemque Graeciam navibus Italiae duo maria maximis classibus firmissimisque praesidiis adornavit, ipse autem, ut Brundisio profectus est, undequinquagesimo die totam ad imperium populi Romani Ciliciam adiunxit: this is a long sentence, which is best broken down into its constituent parts:

• (i) We begin with a cum-clause: Inde cum se in Italiam recepisset...
• (ii) then we get an ablative absolute: ...duabus Hispaniis et Gallia Transalpina praesidiis ac navibus confirmata...
• (iii) ... and another ablative absolute: ...missis item in oram Illyrici maris et in Achaiam omnemque Graeciam navibus...
• (iv) ...before we reach the main clause. It falls into two halves:
  
  • (a) Italiae duo maria maximis classibus firmissimisque praesidiis adornavit;
  • (b) ipse autem ... undequinquagesimo die totam ad imperium populi Romani Ciliciam adiunxit
• (v) the final piece is a temporal ut-clause, inserted into the second half of the main clause: ut Brundisio profectus est.

Before looking at each part in turn, it is worth pondering the organizing principles of the sentence as a whole. The importance of Italy and Rome (and the Roman people) stands out. Italy is the only region mentioned twice – in Italiam; Italiae duo maria – and Cicero concludes the sentence with a reference to the (now extended) empire of the Roman people (ad imperium populi Romani), which thereby emerge at the centre of Pompey’s thoughts and actions. Grammar reinforces the point. First, Pompey is the (implied) subject of all the clauses that contain references to Italy, places therein (Brundisium), or the Roman people: (i) recepisset; (iv) adornavit, adiunxit; (v) profectus est. In contrast, Cicero packs Pompey’s actions in Spain, Gaul, and Greece into two (passive) ablative absolutes: (ii) and (iii). And second, whereas the two Spains and Gaul were furnished praesidiis ac navibus, Pompey secured the two seas and coastlines of Italy in the superlative: maximis classibus firmissimisque praesidiis.

Inde cum se in Italiam recepisset: inde is pulled up front to provide a transition but belongs into the temporal cum-clause (with subjunctive; the tense is pluperfect to indicate a time prior to that of the main verb adornavit, which is in the perfect).

duabus Hispaniis et Gallia Transalpina praesidiis ac navibus confirmata: the plethora of ablatives may be confusing. The noun-phrases that make up the ablative absolute are the chiastically arranged duabus Hispaniis (the reference is to Hispania Citerior, i.e. ‘Nearer Spain’, and Hispania Ulterior, i.e. ‘Further Spain’, of course from the point of view of Italy) and Gallia Transalpina. confirmata (perfect passive participle in the ablative singular) agrees with the nearest one in case, number, and gender, i.e. Gallia Transalpina, but pertains to duabus Hispaniis as well. praesidiis ac navibus are ablatives of means or instrument. All three regions had been Roman provinces for some time. Hispania Citerior and Hispania Ulterior were set up in 197 BC; Gallia Transalpina in Southern France, perhaps better known under the alternative name Gallia Narbonensis, in 120 BC. (The first Roman province was Sicily, established in the wake of the first Punic war in 240 BC.)

missis item in oram Illyrici maris et in Achaiam omnemque Graeciam navibus: in the previous ablative absolute, Cicero began with the nouns (Hispaniis et Gallia) and ended with the participle (confirmata); here he inverts the pattern, beginning with the participle (missis) and ending with the noun (navibus). The focus is on Greece, which Cicero brings out in a climactic tricolon: we start on the West coast of the Greek peninsula (in oram Illyrici), move on to a major province (in Achaiam), and end with the comprehensive omnem Graeciam (also modified by the preposition in + accusative, indicating direction).

Italiae duo maria maximis classibus firmissimisque praesidiis adornavit: Italiae is a possessive genitive dependent on duo maria, which is the accusative object of adornavit. The subject is Pompey (implied). The duo maria of Italy are the Mare Hadriaticum/Superum (today’s Adriatic Sea, separating the Italian from the Balkan Peninsula) and the Mare Tyrrhenum/Inferum (today’s Tyrrhenian Sea).

ipse autem ... undequinquagesimo die totam ad imperium populi Romani Ciliciam adiunxit: undequinquagesimus is put together from unus + de + quinquagesimus, i.e. 1 (unus) taken off (de) the 50th (quinquagesimus) = 49th. The word for ‘50’ is quinquaginta [quinque + ginta]. undequinquagesimo die is an ablative of time. totam agrees with Ciliciam and is emphasized through the hyperbaton.

ut Brundisio profectus est: ut (with the indicative) here has the temporal sense ‘from the time when’. Brundisio is an ablative of separation. Latin does not use a preposition with cities and smaller islands, but if you were to depart from (say) Sardinia, the idiomatic phrase would be ex Sardinia proficisci.

omnes, qui ubique praedones fuerunt, partim capti interfectique sunt, partim unius huius se imperio ac potestati dediderunt: one could suppose that praedones is the antecedent of qui and has been attracted into the relative clause (‘all pirates, anywhere/wherever they were...’); alternatively, one could take praedones predicatively (‘all those, who were pirates anywhere...’). The word order is designed to bring out the antithesis between omnes and unius huius (sc. Pompey).

unius huius ... imperio ac potestati: imperium refers to the right to issue commands attached to the high magistracies of the Roman commonwealth; potestas refers to the legal power associated with a specific role in Roman society, here Pompey’s extraordinary command as defined by the lex Gabinia. unius huius is a possessive genitive.

Idem Cretensibus, cum ad eum usque in Pamphyliam legatos deprecatoresque misissent, spem deditionis non ademit obsidesque imperavit: idem (nominative masculine singular of the pronoun idem, eadem, idem) is the subject of the sentence referring to Pompey. ademit (‘to take something away from somebody’) governs an accusative object (spem deditionis) and a dative (Cretensibus). It is a dative of disadvantage, which is here negated by the non. The -que after obsides, which links ademit and imperavit, has a slightly adversative force: ‘but/rather’.

obsidesque imperavit: imperavit here governs an accusative object of the thing Pompey demanded, i.e. hostages. (If Cicero wanted to say that Pompey gave orders to the hostages, obsides would be in the dative: to command somebody to do something is imperare + dative + ut/ne with subjunctive.)

Ita tantum bellum, tam diuturnum, tam longe lateque dispersum, quo bello omnes gentes ac nationes premebantur, Cn. Pompeius extrema hieme apparavit, ineunte vere suscepit, media aestate confecit: Cicero here returns to § 31, especially the beginning (Testes nunc vero iam omnes orae atque omnes exterae gentes ac nationes) and the end (hoc tantum bellum, tam turpe, tam vetus, tam late divisum atque dispersum quis umquam arbitraretur aut ab omnibus imperatoribus uno anno aut omnibus annis ab uno imperatore confici posse?) Note the repetitions (with variation), which achieve a sense of closure of Cicero’s treatment of the war against the pirates:

quo bello omnes gentes ac nationes premebantur: bello, a reiteration of bellum and the antecedent of quo, has been attracted into the relative clause: ‘a war, by which...’

Cn. Pompeius extrema hieme apparavit, ineunte vere suscepit, media aestate confecit: an elegant, asyndetic (and hence ‘speedy’) tricolon, with a touch of variation in the ablatives: extrema hieme and media aestate are ablatives of time, ineunte vere is a temporal ablative absolute.