Cicero, de Provinciis Consularibus X.25, Piso doesn’t send letters, Gabinius sends them but they are damned, but Caesar’s letters (one presumes) earn him honours as altogether no other man:
vos enim, ad quos litteras L. Piso de suis rebus non audet mittere, qui Gabini litteras insigni quadam nota atque ignominia nova condemnastis, C. Caesari supplicationes decrevistis numero ut nemini uno ex bello, honore ut omnino nemini (Cic. Prov. X.25).
In fact you, to whom L. Piso does not dare to send letters concerning his affairs, you who condemned the letters of Gabinius, with a certain extraordinary censure, and novel dishonour, you voted supplications to C. Caesar, in number as no man, in one war honour as altogether no other.
Later, in XIII.33, we find that a region (Gaul) formerly not known through letters, not even through rumour (fama), has now been tramped all over by Caesar’s army:
… et quas regiones quasque gentis nullae nobis antea litterae, nulla vox, nulla fama notas fecerat, has hoster imperator nosterque exercitus et populi Romana arma peragrarunt. (Cic. Prov. XIII.33)
… and of those regions and those nations, no letters, no voice, no report had before made note to us, these were traversed over by our commander, our army, and by the arms of the Roman people.
And as we know, famously written on by the man himself:
Gallia est omnis divisa in partes tres … (Caesar, de Bello Gallico 1.1.1)
The whole of Gaul is divided into three parts …