As I understand it, the apparent story is that there were approximately 20,000 pirates on Mediterranean at the time that Pompey was tasked with stopping them. He was granted total power of the sea and all lands up to 50 miles inland to do so with the passage of the Lex Gabinia, and with the help of his 13 legates who were each assigned to a portion of the sea, Pompey cleared the sea in just 40 days with a mixture of military (naval) force, promises of pardon for cessation of pirating, the giving of on-land work opportunities (and maybe even land?), among other things.
My professor (who is not a Roman scholar) is skeptical of the accuracy of this version of the story, and I tend to agree based on what little knowledge I have - the removal of 20,000 (supposedly? is this number accurate? can we even know?) pirates, many of which were certainly extremely good at what they did, in just 40 days seems nigh-impossible. However according to him this is a minority view among Roman scholars.
Of course in Roman history and history in general there are many cases of events being revised or exaggerated for purposes of I guess "building legend" would be a good way to put it. So to what extent do you believe this story is exaggerated or not? Is there even a good reason to believe either way conclusively or is it all ambiguous?
e: people have pointed out that I might have mistakes or misinformation which is very possible - like I said I have very little academic knowledge
Of course in Roman history and history in general there are many cases of events being revised or exaggerated for purposes of I guess "building legend" would be a good way to put it
Apart from the fact that the "revision" of historical events in the historical period by the Romans is often vastly overstated (the legendary period is one thing, but not for something in the late Republic, where we have so much evidence), the war against the pirates cannot have been an event exaggerated by later sources, because we have quite a lot of contemporary information about what exactly was going on at the time. In particular we have a preserved speech of Cicero's, the de Imperio, which summarizes Pompey's accomplishments a year after the war with the pirates ended, in an effort to support the Lex Manilia. We know for a fact that Pompey was thought to have cleared the pirates out with dazzling speed because his contemporaries say so--Cicero says that Cilicia was captured 49 days after Pompey left Brundisium. Whether Cicero means that the decisive engagement in Cilicia occurred after 49 days or whether he means that all the strongholds in the province were taken in 49 days I'm not too sure (Plutarch says the last of the pirates surrendered after three months). Perhaps Cicero means that 49 days after the western Mediterranean was cleared Cilicia was assaulted and captured, since Plutarch says that Pompey's fleet returned briefly to Etruria and Brundisium to put on a display against his enemy Piso, and that Pompey departed from Brundisium for Cilicia after Piso backed off. But the fact of the matter is that Pompey's contemporaries very definitely considered the war to have ended unbelievably swiftly
And it's really not all that surprising, though still incredible. For one thing, Pompey was considered at the time of the war against the pirates, to be the greatest general living, and a contender for the greatest general of all time (Cicero calls him a general of divina atque incredibilis virtus, "divine and incredible virtue." Obviously calling him godlike is flattery, but clearly the majority of the state agreed with it, because the Lex Manilia was passed). In only a few years he had been triumphant in all of his battles, and he had already celebrated two triumphs, the first as a private citizen at the age of about 25. If anybody could do it with such speed, it was Pompey, the man was sort of known for the speed with which he could complete his campaigns (coincidentally Plutarch says it took him 40 days to conclude his African campaign, although he reports this as hearsay, not a direct statement from Pompey). Further, when we think of pirates in the Mediterranean we tend not to think of what was really going on. These aren't a bunch of corsairs gallivanting around Jack Sparrow-style from hidden bases scattered around the Mediterranean looking for booty. These are highly organized, efficient fleets operating from a single base. The pirates that were causing so much trouble were those being funded by Mithridates, based in Cilicia. Plutarch specifically says that they had ceased to act like pirates, attacking fleets and cities instead of just raiding and plundering--Cicero supports this when he mentions the cities that were sacked by the pirates, including Ostia itself. Plutarch describes the Cilicians as funded by nobles, including Mithridates, with fortified bases and highly trained and well organized fleets. Now, some of that may be exaggeration (and Plutarch's remarks about rites to Mithras being held in Cilician bases certainly are), but we know from Cicero and others that these pirates were quite formidable and well organized, more like a fleet of raiders than pirates. The campaign was not one of hunting down hundreds (Plutarch says there were a thousand pirate ships, 90 of which were handed over to Pompey in the surrender) of pirate ships scattered individually around the Mediterranean.
I think you're conflating a few things here or making minor errors. By the Lex Gabinia Pompey was awarded 200 ships and 15 legates, according to Plutarch. Appian gives different figures, 270 ships, 25 legates, 120,000 troops and 4,000 cavalry. Both Plutarch and Appian say that Pompey was granted total power to recruit more troops and ships, as well as to exact taxation to fund himself. Plutarch says that with this mandate Pompey recruited even more troops--he gives a figure of 500 ships, 24 legates (actually he says propraetors, but I think he must mean legates here), two quaestors, 120,000 men and 5,000 cavalry, not too far out of line with what Appian says. Whatever the exact number was (and the figures aren't too different), it was large enough to inspire so much confidence that Cicero says that the day that Pompey was awarded the command the price of grain in the city, which had been artificially elevated because of the pirate threat and the sack of Ostia, instantly sank to its normal levels. So it must've been an enormous force to have inspired so much confidence. Plutarch says that the 40-day figure is not the time in which Pompey says that he subdued the pirates, he says that Pompey claimed he had driven the pirates back into Cilicia in 40 days. That's important. The destruction of the pirates was not merely a naval affair, and it was not decided by naval warfare. The pirate threat was eliminated by destroying and capturing the pirates' bases in Cilicia. Appian says that Pompey disposed of his commanders as follows: Tiberius Nero and Manlius Torquatus in Spain and the Pillars of Hercules; Marcus Pomponius off the coast of Gaul and Liguria; Lentulus Marcellinus and Publius Atilius in Africa, Sicily, and Sardinia; Lucius Gellius and Gnaeus Lentulus off the coast of Italy; Plotius Varus and Terentius Varro in the Adriatic; Lucius Sisenna in the Peloponnese, Attica, Euboea, and Thessaly; Lucius Lollius in the Aegean and the Hellespont; Publius Piso in Bithynia, Pontus, the Propontus, and the Black Sea; Metellus Nepos in Lycia, Pamphilia, Cyprus, and Phoenicia. Plutarch says that after the initial dispositions of Pompey's fleet the pirate's fled to Cilicia, where they intended to regroup--it's here that Plutarch says that Pompey said he cleared the Tyrrhenian Sea, the Libyan Sea, Sardinia, Corsica, and Sicily in 40 days. Not the entire Mediterranean, and not the entire pirate threat entirely. though by a combination of diplomacy and land forces capturing the pirates' bases we know from Cicero that Pompey concluded the war shortly thereafter. If Cicero means that 49 days after Pompey set out from Brundisium, after having cleared the pirates from the grain routes, then we should imagine a naval campaign lasting 40 days followed by the army's journey to Cilicia (Plutarch says that they sailed with great haste, only stopping to make sacrifice at Athens, so 30-40 days isn't unreasonable by any means for a journey to Cilicia) and the subsequent capture of the province, which was completed 49 days after the end of the naval campaign. I'm not too familiar with the campaign against the pirates, it's around 5-10 years earlier than the period I'm mostly interested in, so I'd have to check the texts a little more carefully to make absolutely sure, but in any case specifically Pompey was talking about the grain routes from Africa, Sicily, and Sardinia, which was the most important direct cause of the war, as the price of grain had risen rapidly
20k isn't really a lot of people - considering the legion was somewhere around 5k not counting followers. 20k is about four legions and Pompey had 20 legions, according to the New Pauly article on him. 500 ships too, which is just about the biggest ancient navy I'm familiar with. Anyway, we don't have to accept 20k if we don't want to; numbers are usually taken with a grain of salt.
Aside from that, what don't you believe? The 40 day period? The geographical extent? 40 days seems like an exaggeration - Pauly gives three months. In any case we have a date for the lex - 67 - and we also know that Pompey had moved on to the war with Mithridates at the beginning of 66, so we're talking about a matter of months to clean up the pirates.
As for geography, might I propose that this case is a demonstration of the weakness of Rome's promagisterial governance system and lack of central control, rather than an example of Pompey doing something shocking?