Dashing toward the trenches
“It was easy to tell who at Ortolan was once an actor and was now a career waiter. The careerists were older, for one, and precise and fussy about enforcing Findlay’s rules.it was considered polite to at least try to go—and you certainly didn’t discuss auditions, or agents, or anything of the sort with them. Acting was like war, and they were veterans: they didn’t want to think about the war, and they certainly didn’t want to talk about it with naïfs who were still eagerly dashing toward the trenches, who were still excited to be in-country.
Ortolan is a restaurant, Findlays, the restaurant manager.
Question: 『naïfs who were still eagerly dashing toward the trenches, who were still excited to be in-country.』 how to understand [dashing toward the trenches] and [in-country]?