You get free admission to New Hampshire state parks if you are a New Hampshire service member in pay grades E-1 through E-6 in an active or reserve component, or a retired service member. Your spouse or surviving spouse is admitted free as well.
There is nothing to apply for. Show your military ID or retired military ID at the park entrance.
Your active, reserve or retired military ID card, or your dependent ID card if you are a spouse or surviving spouse.