old soldier / veteran, old hand

largely; mostly

a lot / a majority

experience (an experience or one's (overall) experience)

to experience

he / distal demonstrative, something far off removed from both speaker and listener: that / boyfriend

distal demonstrative, something far off removed from both speaker and listener: that, yon / particularly, male personal third person pronoun: he / by extension from he: boyfriend

he; boyfriend

war (conflict involving organized use of arms)

to wage war