Shelly,
My son Zack was 17 years old when he set foot at MCRD in San Diego. He was turned 18 and was deployed for the first time to the Middle East in 1997. He spent that Christmas camped about four miles from the Iraqi border. He deployed several more times before the war in Iraq and served there in 2004 and again in 2005. I worried every hour of the day but I had to trust that he had the best training of any branch of the military, that he and his fellow Marines would be there for each other and I knew as a Alaskan kid he would be able to tough things out. 
Please give your Zac my very best and tell him I appreciate his service ! 
Take care of yourself and remember the Alaskans are Alaska strong !