Donald Ryan McGlothlin of Lebanon, Va., was graduating with a master's in chemistry from Stanford University in California, headed for a PhD, when he decided two years ago to make a sharp turn and travel a less certain road in life.

"He came home after two years at Stanford and said: 'Dad, I just don't feel like I'm doing something that matters. I want to serve my country. I want to protect our lands from terrorists, so I joined the Marines,' " his father, Donald A. McGlothlin Jr., recalled last night.

"Can't you think of some other way to serve your country?" McGlothlin asked his son, who was known as Ryan.

"Dad," the son replied, "I've been privileged, much more so than most Americans. Why should people who aren't as privileged have to bear all the brunt of defending our nation?"

On Wednesday, the 26-year-old McGlothlin, a Marine 2nd lieutenant assigned to Battalion Landing Team, 2nd Battalion, 1st Marine Regiment, based at Camp Pendleton, Calif., was killed during a firefight in Ubaydi, Iraq. His unit was part of Operation Steel Curtain, aimed at cracking down on the insurgency.

Those who knew him in Lebanon, a small town in southwestern Virginia, about 20 miles north of the Tennessee border and 40 miles east of Kentucky, described him as an exceptionally bright, focused person who was also capable of horsing around.

"Whatever he did, he excelled in," said Scott Gilmer, 25, who played on the high school football team with McGlothlin, a defensive end and tight end. "He was a very loyal guy. He didn't say too much. But you could talk to him about anything. He always listened. He was a true friend."

McGlothlin graduated from high school as valedictorian in 1997 and excelled at the College of William and Mary College in Williamsburg, where he was tops in the chemistry department in 2001, according to his father.

While at William and Mary, he enrolled in ROTC but "washed out" because of a medical problem he had with breathing as a child, his father said.

"He still wanted to be in the military," his father said, adding that his son went on to Stanford, where he earned top grades.

The younger McGlothlin then joined the Marine officers program, where he was known for his professionalism, his father said.

"But when the clock struck 5 , so to speak, he was a wisecracker," said his father, a former Circuit Court judge.

McGlothlin's brother Nathan, 28, a lawyer who had just flown to his family's home from Tokyo, said his brother was a great friend.

"I knew he'd be there for me," he said.

His father said he remembered telling his son: "You realize you can be wounded in a way that can change your life or you can lose your life."

"Dad, if I die, I did it doing my duty and protecting my country," he recalled his son replying.

"I console myself with that," he said.