Gosh, how embarrassing! Reading Latin for 20 years and stumped by Julius Caesar!
Haec cum dixisset, procedit extra munitiones QUAEQUE PARS HOSTIUM CONFERTISSIMA EST VISA inrumpit.
Obviously the translation is "where the enemy was most dense" he broke in upon."
But why is there not an ACC. construction as object of INRUMPIT? The constructions given in the mini-Lewis and Short are: quoqunque; in castra, in aciem hostium; cum telis ad sese; ...