HO CHI MINH CITY, Vietnam (AP) -- As the Marines scrambled to the roof of the U.S. Embassy, they locked a chain-link gate on every other floor to slow the throng of panicked Vietnamese civilians sure to come behind them. They knew if the crowd pushed through to the top, they could easily be overrun by hundreds of people desperate to get a seat on one of the last helicopters out of Saigon.
The men barricaded the rooftop door using heavy fire extinguishers and wall lockers and waited nervously as Vietnamese gathered outside rammed a fire truck through an embassy entrance. They could hear looting going on below and watched as cars were driven away and everything from couch cushions to refrigerators was carted out of the offices. South Vietnamese soldiers stripped off their uniforms and threw them into the street, out of fear they would be shot on sight by the northern enemy.
It was still dark when the U.S. ambassador left the roof on a helicopter around 5 a.m. April 30, 1975. A message went out over the radio with his code name, "Tiger, Tiger, Tiger," followed by "Tiger out," to signal that the diplomat was en route to safety.
The sun would be out by the time the remaining Marines realized that the pilots mistakenly believed that the call meant everyone had been evacuated. No one was coming for them, and they had no way to contact U.S. airmen ferrying Vietnamese allies and Americans to aircraft carriers offshore because their radio signals didn't carry that far.
The last U.S. servicemen in Vietnam were stuck alone atop the embassy, hoping someone would realize their mistake before the city fell to rapidly advancing communist forces.
On the 40th anniversary of the fall of Saigon on Thursday, 13 Marines who were there that day returned to what is now Ho Chi Minh City for a memorial ceremony at the site of the old embassy, which is now the U.S. Consulate. They had been in charge of guarding the embassy and the defense attache office beside Tan Son Nhut airport, and were tasked with helping to get the last Americans out.
The days leading up to the end of the Vietnam War were chaotic and exhausting. Northern enemy forces had been sweeping southward for weeks, capturing major South Vietnamese strongholds as they went. Everyone knew it was only a matter of time before the capital, Saigon, also fell. Rumors of a looming bloodbath gripped the city, and Americans along with their South Vietnamese allies were being evacuated on cargo planes from the airport.
Lance Cpl. John Stewart, now 58, of Nacogdoches, Texas, was assigned to take a bus through Saigon to pick up those eligible to leave. He was just 18 and had only been in the country a couple weeks, but he saw anger growing among those on the streets as people realized the end was near and the U.S. was pulling out its last remaining citizens. At one point a rocket hit near the bus and it was shaken by shrapnel, but no one was injured and the evacuation continued.
"We were having to pull people off or physically keep them from getting onto the buses," he said. "You couldn't blame them for wanting to get out, but it had gotten to the point where we could only take those that we absolutely had to. We couldn't take everybody. That's when your brain tells you this is really happening and we've reached the end, and hopefully we'll get out before the end gets here."
Stewart and the others were already shaken after a rocket attack killed two Marines -- Cpl. Charles McMahon and Lance Cpl. Darwin Judge -- early April 29 while they stood guard at the defense attache compound. They would be the last U.S. servicemen to die in a war that killed some 58,000 Americans, up to 250,000 South Vietnamese allies and an estimated 3 million North Vietnamese and civilians.
Thirteen Marines on Thursday placed red roses in front of a plaque and saluted it on the old embassy grounds as taps played.
The bodies of McMahon and Judge were found by Sgt. Kevin Maloney, now 62 of Hollywood, Florida. But there was no time to mourn. Like Stewart, he had to help load buses.
While in the city, he locked eyes with a little boy with light brown hair. He was only supposed to pick up Americans, but he shoved the kid and his mother into one of the front seats anyway, knowing that the child was most likely the son of a GI. He has no idea whether they made it onto a plane and on to America, as many Vietnamese did after being evacuated.
Once the airport became too bombed out to continue operations there, helicopters were ordered to land at the embassy for the final flights.
Maloney was later moved there to help. He spent hours going over the wall to help pull Americans and allies from other countries out of the mob and into the compound so they could be airlifted. He grabbed their hands to pull them up, while beating back the Vietnamese. He left his pistol inside the compound, fearing someone would grab it from his holster and fire shots into the thousands of people.
The scene became so insane that Sgt. Don Nicholas, now 62, of Green, Ohio, was sent to the attache office to guard millions of U.S. dollars before the cash was burned and the compound blown up by the Americans to keep the enemy from raiding it and obtaining classified documents. He later stood watch at the embassy and was shocked when a Vietnamese man, desperate to get into the compound, ran a spike from the gate into his foot as he climbed over the wall. Others began offering "anything and everything" to get inside.
"Women were like, 'Take us in, we'll have sex with you. Here's gold. I have this money, here's jewels. Please just let me in!'" he said. "Within 48 hours, that's all I heard. People begging."
Once the Marines got word that they were to abandon their posts and prepare to evacuate, they moved up to the roof, where they could see parts of the city burning. Many had not slept in two or three days and were running only on adrenaline. No one knew what would happen when the Americans finally left and the city was overtaken by the enemy.
There were about 80 men crowded on the rooftop. One stood guard next to a small window where Vietnamese, who had forced their way inside and through all of the locked gates in the stairwell, were pressed -- hoping and waiting more helicopters were coming for them to board.
A couple of hours passed. No choppers.
"They literally forgot about us," said Master Sgt. Juan Valdez, now 77, of Oceanside, California, who was the detachment commander. "Everybody was in their own thoughts. I was on one side thinking, 'What was going to happen next?' My worst thought was if they were able to direct artillery fire to Tan Son Nhat, what was to keep them from directing artillery fire on the roof?"
The men passed around a bottle of whiskey and waited. Finally, they heard the whirring of helicopter blades. They stripped off their flak jackets, helmets and packs to save weight and stuffed as many people as possible into the last birds that landed. After one last glace to make sure all of his men were gone, Valdez was the last man to board the last helicopter.
On the chopper out ahead of him, Sgt. Douglas Potratz, now 60, from Fullerton, California, watched Saigon burn.
"I felt sad because I felt like we had lost the war and so many lives had been spent on the war here," he said. "I felt like we were entrusted to keep the traditions going and to not let the country go to communism and we had failed, and I felt very low at that time. I felt like it was the end of the world."
The scenes of the women with wailing babies frantically begging to be saved outside the embassy walls haunted his dreams for years, but he said coming back four decades later to the city now called Ho Chi Minh City with the same men he left with so long ago has helped him heal.
"When I saw that that the country had moved forward, it gave me a little peace in my mind and let me move forward mentally knowing that it wasn't frozen in time anymore," he said. "Things do progress. Things do move forward, and I could put the past away and have better memories instead of just bad memories about this country."
Mason covered Vietnam as an AP correspondent based in Hanoi from 2003-2012. Follow her at twitter.com/MargieMasonAP