OLATHE, Kansas -- With more than 16 million Americans who served in World War II, only a fraction of them still live today. Even fewer can claim to have reached the age of 100. John J. O’Leary, a retired Marine first lieutenant, is one of the lucky few.

He celebrated his 100th birthday at the Evergreen Community of Johnson County, Olathe, Kansas, Dec. 23, 2016.

O’Leary saw combat on Guam and witnessed the bombardment on Iwo Jima. Even after the war ended, his pride for the Marine Corps never faded.

“The first time I met him I was immediately impressed by his love for the Marine Corps,” said Col. Thomas M. Fahy, commanding officer of Combat Logistics Regiment 4, 4th Marine Logistics Group, Marine Forces Reserve. “We are losing World War II veterans every day. I think it is important to have their stories memorialized.”

Fahy learned about O’Leary through a website his unit was using to promote their 241st Marine Corps Birthday Ball in November. O’Leary reached out to the unit and Fahy traveled to the Evergreen Community to meet him.

“I knew we had to have him as the guest at our birthday ball,” Fahy said. "He is very enjoyable to be around, he is very sharp and he has a great sense of humor."

With his wife Dixie accompanying him as his date, O’Leary attended the ball as the oldest Marine present and the only person in attendance to have served in World War II. His story dates back almost 75 years.

When John J. O’Leary enlisted in the Marine Corps in the aftermath of the attack on Pearl Harbor, he had no idea what was in store for him.

“I didn’t know anything about the military,” O’Leary said. “I was the first of three brothers to serve in World War II. I joined because of all the good publicity the Marine Corps was getting at the time.”

In 1942, after attending recruit training at Parris Island, South Carolina, and radio operator school in New York, O’Leary volunteered to be part of the newly formed 4th Raider Battalion at Camp Pendleton, California. There O’Leary served as Col. James Roosevelt’s personal radio operator.

“He was the president’s son,” O’Leary said. “He was a nice guy and a good officer.”

However, O’Leary was not fated to stay with the Raiders. The colonel learned O’Leary had a college degree and sent him to officer candidate school in Quantico, Virginia.

“I was a private first class and had been in the Corps for 18 months,” O’Leary said. “Our entire class was made up of all enlisted men.”

In June 1944, after finishing all of his training, O’Leary was sent among the first replacements for the 3rd Marine Division in Guam. He was assigned to take over a shore beach party with 3rd Joint Assault Signal Company. His company was there through the retaking of the island from the Japanese.

“I had to become a good ducker,” O’Leary said with a wry smile. “I spent a year and a half on Guam. That’s a long time. I have a lot of memories.”

On Feb. 19, 1945, O’Leary was assigned to 3rd Marine Regiment and waited from a troop ship to land on Iwo Jima. What he didn’t know at the time was that his regiment was the only regiment out of the nine present that was held in reserve. Although he witnessed the battle from the sea, he never saw the shore.

“His ship became a hospital ship,” Fahy said. “Many of the dead and wounded from Iwo Jima were transferred to his ship.”

As the battle continued, O’Leary witnessed tables in the galley converted into operating tables.

“Those were rough times,” O’Leary said. “There were a lot of dead and injured.”

In his room, among images of friends and family, hangs an original copy of the photograph of the second flag-raising on Iwo Jima, signed by photographer Joe Rosenthal.

“One morning on Guam, after Iwo Jima, I looked out my tent and saw a small guy signing photographs which he had just made of the flag raising,” O’Leary said. “At the time, I didn’t know how significant the photo would become.”

More than 70 years after the photo was taken and the war ended, in a small retirement home room, O’Leary still holds the Marine Corps and his memories of his service close to his heart.

"His love of his country and his love of his Marine Corps is undying," Fahy said. "I'm very proud to have met him and honored to have spent the short amount of time I have spent with him. I look forward to seeing him at our next birthday ball."

This year also marks the 100th anniversary of the Marine Corps Reserve. By the end of World War II, Reserve Marines made up 70 percent of total wartime Marine Corps personnel, including O’Leary. Having witnessed generations of Marines put on the uniform after him, O’Leary is confident that the Corps is still in good hands.

"The Marine Corps is a great organization," O'Leary said. “It’s full of a lot of dedicated individuals. I’m very proud of my time as a Marine.”