4.20.1Exiguā parte aestātis reliquā Caesar, etsī in hīs locīs, quod omnis Gallia ad septentriōnēs vergit, mātūrae sunt hiemēs, tamen in Britanniam proficīscī contendit, quod omnibus ferē Gallicīs bellīs hostibus nostrīs inde subministrāta auxilia intellegēbat, et sī tempus annī ad bellum gerendum dēficeret, tamen magnō sibi ūsuī fore arbitrābātur, sī modo īnsulam adiisset, genus hominum perspexisset, loca, portūs, aditūs cognōvisset;Though only a small part of the summer was left, and winters come early in these parts because all Gaul faces north, Caesar nevertheless hurried to set out for Britain, because he understood that in almost all the Gallic wars help had been sent from there to our enemies; and even if the season of the year was too short for waging war, he still thought it would be of great use to him if he merely visited the island, observed the kind of people, and learned about the places, harbors and approaches;Note. Exiguā parte aestātis reliquā: ablative absolute, 'with a small part of summer left'. magnō sibi ūsuī fore: double dative, 'would be of great use to him'; fore = futūrum esse. The sī modo clause uses pluperfect subjunctives for future perfects in reported thought. 4.20.2quae omnia ferē Gallīs erant incognita.almost all of which were unknown to the Gauls. 4.20.3Neque enim temerē praeter mercātōrēs illō adit quisquam, neque hīs ipsīs quicquam praeter ōram maritimam atque eās regiōnēs quae sunt contrā Galliam nōtum est.For hardly anyone goes there without good reason except traders, and even they know nothing except the sea coast and the regions that lie opposite Gaul.Note. illō: adverb, 'to that place'. temere: 'without good reason, casually'. Note the strong negatives neque … quisquam, neque … quicquam.
4.20.4Itaque vocātīs ad sē undique mercātōribus, neque quanta esset īnsulae magnitūdō neque quae aut quantae nātiōnēs incolerent, neque quem ūsum bellī habērent aut quibus īnstitūtīs ūterentur, neque quī essent ad maiōrem nāvium multitūdinem idōneī portūs reperīre poterat.And so, although he called traders to him from every side, he could not find out how large the island was, what peoples lived there or how large they were, what experience of war they had or what customs they followed, or what harbors there were that were suitable for a large number of ships.Note. A string of indirect questions (quanta esset … quae aut quantae … quem ūsum … quī essent) all depending on reperīre poterat at the very end.