Editor's note: Jake Tapper is an anchor and chief Washington correspondent for CNN. He is author of the best-selling book about the Combat Outpost Keating attack in Afghanistan, "The Outpost: An Untold Story of American Valor."
Washington (CNN) -- His eyes moist and lower lip trembling, Clint Romesha nodded haltingly at family, comrades, military brass and the president standing to applaud him for receiving the nation's highest military decoration, the Medal of Honor.
He never smiled during the White House ceremony on Monday and later explained why in a statement to reporters.
"I stand here with mixed emotions of both joy and sadness today," he said, describing how he felt "conflicted" about the medal around his neck.
"The joy comes from recognition from us doing our jobs as soldiers on distant battlefields," said Romesha, a former Army staff sergeant dressed in full uniform that included a cavalry hat. "But it is countered by the constant reminder of the loss of our battle buddies - my battle buddies, my soldiers, my friends."
For "conspicuous gallantry ... at the risk of his life above and beyond the call of duty," Romesha, 31, received the honor at an emotional ceremony lightened by his rambunctious toddler son.
In conferring the medal, President Barack Obama described the conditions faced by Romesha and 52 other soldiers when they came under attack from mortar, rocket-propelled grenade, machine-gun and sniper fire on October 3, 2009, at Combat Outpost Keating in the mountains of eastern Afghanistan.
A military investigation later described the outpost as indefensible against the higher-ground positions surrounding it, and Obama noted the challenge that Romesha's unit faced from the estimated 300 Taliban insurgents.
Explosions from the dawn attack "shook them out of theirs beds and sent them rushing for their weapons, and soon the awful odds became clear," Obama said.
"What happened next has been described as one of the most intense battles of the entire war in Afghanistan," the president continued. "The attackers had the advantage, the high ground, the mountains above, and they were unleashing everything they had -- rocket-propelled grenades, heavy machine guns, mortars, snipers taking aim."
Romesha and his men "had never seen anything like it," Obama said.
"With gunfire impacting all around him, Clint raced to one of the barracks and grabbed a machine gun," the president said. "He took aim at one of the enemy machine teams and took it out. A rocket-propelled grenade exploded, sending shrapnel into his hip, his arm and his neck, but he kept fighting, disregarding his own wounds and tended to an injured comrade instead."
Later in the battle, Romesha and his team charged more than 100 yards through enemy fire to reach wounded soldiers in the outpost, Obama added.
The audience on Monday included relatives of the eight soldiers killed in the battle, and Obama paid tribute to the efforts by Romesha and his fellow soldiers to bring them back.
"Our troops should never ever be put in a position where they have to defend the indefensible," Obama said. "That's what these soldiers did for each other in sacrifice driven by pure love, and because they did, eight grieving families were at least able to welcome their soldiers home one last time."
Before the East Room ceremony, the militaristic and somber atmosphere was lightened by Romesha's son, Colin, who climbed the podium and examined the lectern, briefly playing hide-and-seek with the bemused onlookers.
It took a military escort to entice Colin to his mother's arms in the first row, and when Obama spoke a few minutes later, he prompted chuckles in pointing out the boy's exuberant nature.
"Colin is not as shy as Clint," Obama said. "He was in the Oval Office and he was racing around pretty good and sampled a number of apples before he found the one that was just right."
Romesha was invited to be the guest of first lady Michelle Obama Tuesday at the president's State of the Union address. But he declined the invitation, telling CNN that he has decided to spend the evening with friends from his former unit, Black Knight Troop, 3-61 CAV, his wife Tammy -- with whom he celebrates a wedding anniversary Tuesday -- and their families.
Romesha is the fourth living person to receive the nation's highest military decoration for actions in Afghanistan or Iraq.
The battle at Combat Outpost Keating raged for more than 12 hours. When it ended, with Romesha and others having held onto the outpost, more than half of their 53-soldier contingent had been killed or wounded.
Despite his own wounds, Romesha led a charge across the outpost that regained control of the ammunition supply depot. In doing so, he ignored an order to hold his position, pretending the radio was broken.
The U.S. military closed the heavily damaged outpost three days later, destroying what remained to prevent it from aiding insurgents in any way.
A few months later, a U.S. military investigation found that measures taken to protect the outpost were lax, and critical intelligence and reconnaissance assistance had been diverted from the base.
CNN's Chelsea J. Carter contributed to this report.