§7.72.1Quibus rebus cognitis ex perfugis et captivis, Caesar haec genera munitionis instituit.
Having learned these things from deserters and captives, Caesar established the following types of fortification.
Fossam pedum viginti directis lateribus duxit, ut eius fossae solum tantundem pateret quantum summae fossae labra distarent.
He dug a trench of twenty feet with vertical sides, so that the bottom of this trench should extend just as far as the edges of the trench at the top were wide apart.
§7.72.2Reliquas omnes munitiones ab ea fossa pedes quadringentos reduxit, [id] hoc consilio, quoniam tantum esset necessario spatium complexus, nec facile totum corpus corona militum cingeretur, ne de improviso aut noctu ad munitiones hostium multitudo advolaret aut interdiu tela in nostros operi destinatos conicere possent.
He withdrew all the rest of the fortifications four hundred feet from that trench, with this intention, because he had of necessity enclosed so large a space and the whole circuit could not easily be manned by a ring of soldiers, lest either a multitude of the enemy should suddenly or by night rush up to the fortifications, or by day they should be able to cast weapons at our men who were employed on the work.
§7.72.3Hoc intermisso spatio duas fossas quindecim pedes latas, eadem altitudine perduxit, quarum interiorem campestribus ac demissis locis aqua ex flumine derivata complevit.
Leaving this interval, he drew two trenches fifteen feet broad, of the same depth; the inner of these, in the flat and low places, he filled with water drawn from the river.
§7.72.4Post eas aggerem ac vallum duodecim pedum exstruxit.
Behind these he constructed a rampart and breastwork of twelve feet.
Huic loricam pinnasque adiecit grandibus cervis eminentibus ad commissuras pluteorum atque aggeris, qui ascensum hostium tardarent, et turres toto opere circumdedit, quae pedes LXXX inter se distarent.
To this he added a parapet and battlements, with large "cervi" projecting at the junctions of the screens and the rampart, to delay the ascent of the enemy, and he surrounded the entire work with towers, which were eighty feet apart from one another.