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In this March 29, 1973 photo, Camp Alpha, Uncle Sam’s out processing center, was chaos in Saigon. Lines of bored soldiers snaked through customs and briefing rooms. As the last U.S. combat troops left Vietnam 40 years ago, angry protesters still awaited them at home. North Vietnamese soldiers took heart from their foes' departure, and South Vietnamese who had helped the Americans feared for the future. While the fall of Saigon two years later — with its indelible images of frantic helicopter evacuations — is remembered as the final day of the Vietnam War, Friday marks an anniversary that holds greater meaning for many who fought, protested or otherwise lived it. (AP Photo) ( Vietnam Withdrawal Anniversary )

DA NANG, VIET NAM: Photograph dated 1973 showing a North Vietnamese Army (NVA) officer (R) overseeing the departure of US military personnel at Da Nang airport, following the January 1973 signing of the Paris accords. (Photo credit should read AFP/Getty Images) ( APP2000021479308 )

Viet Cong and North Vietnamese members of the joint military commission (foreground) snap pictures of U.S. troops as they board an Air Force plane for the flight home from Saigon's Tan Son Nhut Air Base, March 27, 1973. Withdrawal of these and other U.S. military personnel resumed after it was delayed to insure release of American POWs captured in Laos. (AP Photo/Neal Ulevich) ( Vietnam 1973 )

In this April 2, 1973 photo, President Richard Nixon and South Vietnamese President Nguyen Van Thieu are in profile as they listen to national anthems during arrival ceremonies for Thieu at the Western White House in San Clemente, Calif. As the last U.S. combat troops left Vietnam 40 years ago, angry protesters still awaited them at home. North Vietnamese soldiers took heart from their foes' departure, and South Vietnamese who had helped the Americans feared for the future. While the fall of Saigon two years later — with its indelible images of frantic helicopter evacuations — is remembered as the final day of the Vietnam War, Friday marks an anniversary that holds greater meaning for many who fought, protested or otherwise lived it. (AP Photo) ( Vietnam Withdrawal Anniversary )

An American GI takes a nap atop his luggage as he and other troops wait to begin outprocessing at Camp Alpha in Saigon, March 27, 1973, as withdrawal of U.S. troops resume after a 10-day dispute over POWs. All U.S. troops are due out Thursday. (AP Photo/Chick Harrity) ( Vietnam Troops Leaving 1973 )

Surrounded by luggage of other departing GIs, U.S. Air Force airman reads paperback novel as he waits to begin processing at Camp Alpha on Saigon's Tan Son Nhut airbase in Saigon as troop withdrawals resume after 10 day-delay, March 27, 1973. More than 900 will leave with all U.S. troops out by Thursday. (AP photo/Charles Harrity) ( Vietnam 1973 )

In this April 10, 1973 photo, Gen. Alexander M. Haig, center, is greeted by acting ambassador Charles Whitehouse, left, and another embassy official following Haig's arrival, in Saigon, the last stop in his whirlwind tour of Indochina. The trip was made at the behest of President Nixon. As the last U.S. combat troops left Vietnam 40 years ago, angry protesters still awaited them at home. North Vietnamese soldiers took heart from their foes' departure, and South Vietnamese who had helped the Americans feared for the future. While the fall of Saigon two years later — with its indelible images of frantic helicopter evacuations — is remembered as the final day of the Vietnam War, Friday marks an anniversary that holds greater meaning for many who fought, protested or otherwise lived it. (AP Photo/Neal Ulevich) ( Vietnam Withdrawal Anniversary )

In this March 31, 1973 photo, Adm. John S. McCain Jr., left, and his son, Lt. Cmdr. John S. McCain III meet for the first time in Jacksonville, Fla. As the last U.S. combat troops left Vietnam 40 years ago, angry protesters still awaited them at home. North Vietnamese soldiers took heart from their foes' departure, and South Vietnamese who had helped the Americans feared for the future. While the fall of Saigon two years later — with its indelible images of frantic helicopter evacuations — is remembered as the final day of the Vietnam War, Friday marks an anniversary that holds greater meaning for many who fought, protested or otherwise lived it. (AP Photo) ( Vietnam Withdrawal Anniversary )

In this March 29, 1973 photo, Camp Alpha, Uncle Sam’s out processing center, was chaos in Saigon. Lines of bored soldiers snaked through customs and briefing rooms. As the last U.S. combat troops left Vietnam 40 years ago, angry protesters still awaited them at home. North Vietnamese soldiers took heart from their foes' departure, and South Vietnamese who had helped the Americans feared for the future. While the fall of Saigon two years later — with its indelible images of frantic helicopter evacuations — is remembered as the final day of the Vietnam War, Friday marks an anniversary that holds greater meaning for many who fought, protested or otherwise lived it. (AP Photo) ( Vietnam Withdrawal Anniversary )

(FILES) Photo taken 27 January 1973 in Paris, of US, South Vietnamese, North Vietnamese, and Viet Cong representatives signing the long-sought cease-fire agreement that ended the war in Viet-Nam. According to the 1st article of the peace agreement, the "United States and all other countries respect the independence, sovereignty, unity, and territorial integrity of Viet-Nam as recognized by the 1954 Geneva Agreements on Viet-Nam". Were present Nixon's chief foreign policy adviser US Henry A. Kissinger (R) and North Vietnam's Le Duc Thos (2d row 2d L). AFP PHOTO (Photo credit should read -/AFP/Getty Images) ( PAR2003091675748 )

In this Wednesday, April 12, 1973 photo, Daniel Ellsberg, co-defendant in the Pentagon Papers trial, talks with newsmen after he testified in Los Angeles. Next to him is his wife, Patricia. Ellsberg, who vividly described his journey to disillusionment in Vietnam on Wednesday, will climax that story on Thursday, telling jurors how he risked his government career to copy the Pentagon Papers, hoping to end the war. As the last U.S. combat troops left Vietnam 40 years ago, angry protesters still awaited them at home. North Vietnamese soldiers took heart from their foes' departure, and South Vietnamese who had helped the Americans feared for the future. While the fall of Saigon two years later — with its indelible images of frantic helicopter evacuations — is remembered as the final day of the Vietnam War, Friday marks an anniversary that holds greater meaning for many who fought, protested or otherwise lived it. (AP Photo) ( Vietnam Withdrawal Anniversary )

In this March 29, 1973 photo, In a curious ending to a bizarre conflict, American troops board jets under the watchful eyes of North Vietnamese and Viet Cong observers in Saigon. As the last U.S. combat troops left Vietnam 40 years ago, angry protesters still awaited them at home. North Vietnamese soldiers took heart from their foes' departure, and South Vietnamese who had helped the Americans feared for the future. While the fall of Saigon two years later — with its indelible images of frantic helicopter evacuations — is remembered as the final day of the Vietnam War, Friday marks an anniversary that holds greater meaning for many who fought, protested or otherwise lived it. (AP Photo) ( Vietnam Withdrawal Anniversary )

PARIS, FRANCE - JANUARY 23, 1973: US National Security Adviser Henry Kissinger (R) and Le Duc Tho, leader of North Vietnam delegation, leave the house where they met regarding the enforcement of the Paris Peace Accords, 23 January 1973 in Paris, France. (Photo by AFP/Getty Images) ( D054450020.jpg )

WASHINGTON - JANUARY 24, 1973: US president Richard Nixon (L) receives participants of Congress leaders and foreign Secretary of State Henry Kissinger (R), after the signing of ceasefire agreement in Vietnam, 24 January 1973 in Washington. (Photo by AFP/Getty Images) ( D054450014.jpg )

PARIS, FRANCE - JANUARY 23, 1973: US National Security Adviser Henry Kissinger (R) shakes hand with Le Duc Tho, leader of North Vietnam delegation, after the signing of the Paris Peace Accords on 23 January 1973 in Paris, France. (Photo by AFP/Getty Images) ( D054450016.jpg )

In this Thursday, May 3, 1973 photo, Henry Kissinger, President Nixon's foreign affairs adviser, briefs newsmen on Nixon's annual State the World report to Congress at the White House in Washington. The report states that North Vietnam risks renewed war with the Untied States unless it lives up to the Vietnam cease-fire. As the last U.S. combat troops left Vietnam 40 years ago, angry protesters still awaited them at home. North Vietnamese soldiers took heart from their foes' departure, and South Vietnamese who had helped the Americans feared for the future. While the fall of Saigon two years later — with its indelible images of frantic helicopter evacuations — is remembered as the final day of the Vietnam War, Friday marks an anniversary that holds greater meaning for many who fought, protested or otherwise lived it. (AP Photo/Harvey Georges) ( Vietnam Withdrawal Anniversary )

PARIS, FRANCE: Photo taken 27 January 1973 in Paris, of US, South Vietnamese, North Vietnamese, and Viet Cong representatives signing the long-sought cease-fire agreement that ended the war in Viet-Nam. According to the 1st article of the peace agreement, the "United States and all other countries respect the independence, sovereignty, unity, and territorial integrity of Viet-Nam as recognized by the 1954 Geneva Agreements on Viet-Nam". Was present North Vietman's Nguyen Duy Trinh (4thL). AFP PHOTO (Photo credit should read AFP/Getty Images) ( PAR2003091675737 )

The head of American delegation, State Secretary William Rogers is given documents to sign the first act of cease fire agreement during the international peace conference on Vietnam, 27 January 1973 in Paris, the final act will be signed the 02 March. (Photo credit should read STAFF/AFP/Getty Images) ( APP2000051913353 )

Spc 4 Scott McPherson of California carries an appropriate sign he made during his Vietnam tour of duty as he boards a bus in Saigon, Jan. 30, 1973, which will take him to the airport for a flight back to the United States. Under terms of the ceasefire agreement, all U.S. troops must be withdrawn from Vietnam within 60 days after signing of the pact. (AP Photo) ( Vietnam US Troops Withdrawal 1973 )

Marijuana-sniffing dog, at right, checks over luggage of departing U.S. troops as they process through customs at Tan Son Nhut's Camp Alpha on Feb. 1, 1973. Camp is the main processing center in South Vietnam for troop withdrawals. All troops must be out of Vietnam by the end of March. (AP Photo) ( Vietnam War US troops withdraw 1973 )

A bon voyage banner stretches overhead in Da Nang, South Vietnam, as soldiers march down a street following a farewell ceremony for some of the last U.S. troops in the country's northern military region, March 26, 1973. About 800 men are still stationed in Da Nang and are to remain there until the release of the American POWs is completed. (AP Photo) ( Vietnam US Troop Withdrawal 1973 )

A U.S. airman, his pet dog following behind him, walks past the quiet and deserted hangars at Da Nang Air Base, Jan. 29, 1973. Four thousand Americans here are preparing to go home, but this airman's dog will not be allowed to go home with him. (AP Photo/Dang Van Phuoc) ( All Quiet In Da Nang )