Tacticus mentions Vindex very briefly in his Annals – ‘after the revolt of Gaius Julius Vindex it* was interpreted as a sign portending future retribution’ (*Nero’s dedication of a dagger to Jupiter Vindex, the Avenger). Just as he was getting to the revolt and end of Nero, Tacitus, stopped writing, died, or we have lost the manuscript.
Suetonius mentions Vindex in his Twelve Lives of the Caesars – specifically in Nero’s and Galba’s but he tells us nothing useful about the details of the military revolt. It’s political biography he’s writing not military history.
Philostratus puts a nice little speech into Vindex’s mouth to rally support but its almost certainly Philostratus and not Vindex we are hearing (at least 2 centuries after the event).
This: Literary Sources gives a quick run through the literary sources for Nero’s reign (ignore the first bit unless you want a quick run through of Nero’s reign) and go to the literary sources bit.
If you want to read the relevant bits of Cassius Dio they are on line: Cassius Dio
Not sure if that is good or bad from the campaign point of view. We don’t know much – but on the other hand – we don’t know much!
That means I can play it by ear without fear of someone saying I am wrong. A few retired Legionaries leading groups of what amount to Militia, with even a few enthusiasts who have dug out granpa’s Sword, taken all their clothes off and painted themselves Blue*!