WASHINGTON (CNN) -- Frank Woodruff Buckles was just 15 years old when he joined the U.S. Army. Soon, he was deployed to war and headed overseas on the Carpathia -- the same ship used in the rescue mission of the Titanic.
World War I veteran Frank Buckles entered the Army at age 15. "I didn't lie," he said with a laugh this week.
He drove ambulances in Britain and France for soldiers wounded during World War I.
A few decades later, Buckles was in the Philippines as a civilian, on December 7, 1941, the day Japan attacked Pearl Harbor. He was taken as a prisoner of war for 39 months in Manila, eating his meals out of a single tin cup.
More than 60 years later, he still clings to that cup, the one that sustained his life. Weathered with age, the cup has flecks of white paint chipped off. He keeps it as a reminder of his sacrifice for the country he so loves. He also still has his dog tags.
At age 107, there's not much the war veteran, POW and West Virginia farmer hasn't seen. But this week, this quietly accomplished man was humbled.
Buckles, the last known surviving World War I U.S. veteran, met the president of the United States and received a standing ovation at the Pentagon.
"I didn't lie; nobody calls me a liar," he said with a chuckle, referring to how he became a soldier at just 15.
Speaking with a hushed, deep voice, he conceded, "I may have increased my age."
He spoke from a wheelchair, dressed in a dark blazer with his military medals pinned over his heart. Those in attendance clung to his words.
"We cherish the chance to say thank you in person to Cpl. Frank Buckles," Defense Secretary Robert Gates said, before unveiling a portrait of him.
"Mr. Buckles has a vivid recollection of historic times, and one way for me to honor the service of those who wear the uniform in the past and those who wear it today is to herald you, sir, and to thank you very much for your patriotism and your love for America," the president said, seated with Buckles in the Oval Office.
Buckles' tour of Washington was part of a series of events to honor the veterans of World War I, which included the opening of a photographic display at the Pentagon on Thursday.
There will be nine formal portraits on permanent exhibition at the Pentagon. All were donated by David DeJonge who spent a decade finding and photographing the last of the World War I vets.
DeJonge wants a more elaborate memorial in Washington to honor the veterans.
For now, the only public site is an unpretentious gazebo near the Jefferson Memorial established by the city of Washington D.C.
Buckles visited the site Thursday afternoon. Watch Buckles view the memorial
"I think it was a very nice idea," he said after he and an aide toured the structure.
But Buckles noticed the memorial is not national but built primarily to honor veterans from the District of Columbia.
"I can read here that it was started to include the names of those who were local," Buckles said.
He was greeted at the site by two young Army Medical Corps candidates in training at the Uniformed Services University of the Health Sciences in Bethesda, Maryland.
"It's just an honor to see somebody that served so much before us, to be in the same shoes as him, like, a century later," said Reeme Sikka, 22.
One passerby, Vietnam veteran Zeke Musa, was embarrassed by the unkempt condition of the memorial.
"These guys served their country, you know. It's a shame," he said.
According to an autobiography the Pentagon released, Buckles was eager to join the war. He said his recruiter in the summer of 1917 told him that "the ambulance service was the quickest way to get to France," so he trained in trench casualty retrieval.
Buckles eventually served as an officer's escort in France before joining a transport detail for German prisoners of war. He now lives on his family's cattle farm near Charles Town, West Virginia.
By the end of Thursday, the last of America's World War I doughboys was clearly effected by the day's events.
"I feel honored," he said. E-mail to a friend
CNN's Paul Courson contributed to this report.