in the frontline

на передовій; на фронті; на лінії фронту; на передньому краї; 'на нулі' (`he paid attention to the upcoming missions and made sure his kids were always in the front line` - kids в цьому контексті означає soldiers; 'he had been in the front line of the army that confronted the team on the ridge', -  from `Lone Survivor` by Marcus Luttrell)