WASHINGTON -- President Barack Obama will correct a historical act of discrimination next month when he awards the Medal of Honor, the nation's highest commendation for combat valor, to a group of Latino, Jewish and African-American veterans who were passed over because of their racial or ethnic backgrounds.

The unusual presentation will culminate a 12-year Pentagon review ordered by Congress into past discrimination in the ranks and will hold a particular poignancy when conducted by the nation's first African-American president.

Although the review predates Obama's tenure, he has made addressing discrimination in the military -- including ending the ban on gay and lesbian service members -- a priority as commander in chief.

With the ornate White House East Room as backdrop, the March 18 ceremony will mark another step to revisit a history of discrimination in the armed forces as the nation's demographics and social values shift.

The recipients, whom the White House announced Friday afternoon, served in World War II, Korea and Vietnam. Collectively, their award ceremony will mark the single largest group of Medal of Honor recipients since World War II, when more than two dozen service members were honored in that conflict's last days.

Just three of the 24 veterans who will be honored are still alive. All but five of the soldiers are Latino, Jewish or African-American, including Melvin Morris, a former Green Beret who was wounded three times on a mid-September day in 1969 recovering the body of his fatally wounded master sergeant from a jungle ambush in the Chi Lang district of northeastern Vietnam.

"I never thought much about it and didn't until recently," said Morris, 72, who was decorated three times for his service in Vietnam and retired from the Army after 22 years. "But I think that this is something the military always should address because, in almost every process we have, someone is overlooked."

The unusual historical accounting began in 2002 when Congress, as part of the military spending bill, ordered the Pentagon to look into whether Jewish and Latino service members had been passed over unfairly for the nation's highest military honor.

Defense Department officials said there was specific evidence to suggest such discrimination may have existed in the ranks, including instances in which Latino and Jewish soldiers apparently changed their names to hide their ethnicity.

The congressional order spanned the period from December 1941 through September 2001.

The project was an enormous undertaking that sent military personnel officials searching for lost records and battlefield histories.

Officials from each service branch focused on service members who had been awarded the second-highest medal for gallantry: the Distinguished Service Cross for the Army, the Air Force Cross for that branch, and the Navy Cross for the Navy and Marine Corps.

Although that narrowed the review, the Army alone identified more than 600 records that needed reassessment. The smaller branches found 275 among them.

"It's hard to be awarded the medal for a single person, and to go back for all those potential candidates, that is a very demanding scope and record-retrieval task," said a defense official. "It was very time-consuming. But we wanted to make sure that, as a process, we did it correctly and that the Medal of Honor process itself was honored."

The reassessment sent a host of candidates through the various service boards that decide on Medal of Honor recipients and then to the Joint Chiefs for approval. Two dozen veterans -- all from the Army -- emerged as worthy of an upgrade to the Medal of Honor.

They include 17 Latino soldiers, such as Santiago Erevia, a former specialist four who served in Vietnam as a radio telephone operator in Company C, 1st Battalion (Airmobile), 501st Infantry of the 101st Airborne Division. He will receive the Medal of Honor at the March 18 ceremony for "courageous actions" during a search-and-clear mission near Tam Ky, Vietnam.

"We've wondered why he didn't receive it the first time and thought it may have been because of his name," said Jesse Erevia, 41, his son, who lives in San Antonio, not far from his father.

Erevia said his father had "some issues" with the Vietnam War, mainly concerning its rationale, and has mixed feelings about military honors in general. But the family is eager to attend the White House ceremony next month to see him receive an award they have long felt he deserved.

The third living veteran is Jose Rodela, a former sergeant first class from Corpus Christi, Texas, who will receive the medal for bravery during fighting in Phuoc Long province, Vietnam, in September 1969.