WASHINGTON —

President Obama bestowed the nation’s highest military honor, the Medal of Honor, on Army Staff Sgt. Ty Carter on Monday, saluting the veteran of the Afghan war as “the essence of true heroism,” still engaged in a battle against the lingering emotional fallout of war.

Carter risked his life to save an injured soldier, resupply ammunition to his comrades and render first aid during intense fighting in a remote mountain outpost four years ago.

“As these soldiers and families will tell you, they’re a family forged in battle, and loss, and love,” Obama said as Carter stood at his side and members of his unit watched in the White House East Room.

As an Army specialist, Carter sprinted from his barracks into a ferocious firefight, a day-long battle on Oct. 3, 2009, that killed eight of his fellow soldiers as they tried to defend their outpost — at the bottom of a valley and surrounded by high mountains — from the onslaught of a much larger force of Taliban and local fighters.

Still suffering from post-traumatic stress disorder, Carter stood nearly emotionless during the ceremony, although a faint smile crossed his face near the end that turned into a broad grin as Obama hung the metal and its blue ribbon around his neck and the audience answered with a rousing standing ovation.

Later, Carter told reporters outside the White House that receiving the medal had been “one of the greatest experiences” for his family and that he would “strive to live up to the responsibility.”

He also said he wanted to help the American public to better understand the “invisible wounds” still afflicting him and thousands of others.

“Only those closest to me can see the scars,” Carter said, reading his statement. He said Americans should realize that those suffering from post-traumatic stress disorder “are not damaged, they are just burdened by living when others are not.”