This simile speaks of the group as acting as a single person. They all acted together in exactly the same way. AT: "as if they were a single man" (See: [[rc://en/ta/man/translate/figs-simile]])
These two clauses say basically the same thing twice for emphasis. They can be combined. The words "none ... go" and "none ... return" emphasizes how the people will continue to stay there. They can be stated in positive form. AT: "We will all stay here" (See: [[rc://en/ta/man/translate/figs-parallelism]] and [[rc://en/ta/man/translate/figs-litotes]])