This memoir describes my four-year Marine Corps experience, especially the thirteen-month tour in Vietnam. Brief background information begins the narrative. It ends with a few words on the return to civilian life. I first wrote about these experiences as an aid to adjusting to life at home after the marines: it was helpful therapy. About fifty years later, with extra time after retiring, I revisited the experience and rewrote the memoir into its present form. The title, Add 50 , is a reference to the commands given by forward observers to guide mortar rounds to the intended target. My assignment during most of my time in-country was 81mm mortar forward observer for Charlie company. It was a difficult and dangerous task which I performed as best I could. The story covers these difficulties and is an accurate personal account of one marine's military service.