The U.S. Coast Guard led a water evacuation of more than 500,000 people from Manhattan following the Sept. 11, 2001 terror attacks on the World Trade Center towers in an action that moved more people from the island than the 1940 evacuation of Allied troops from France, according to a new oral history of former USCG commandant, Adm. James Loy.

Following the collision of the two planes into the towers, hundreds of thousands were trapped on the southern tip of the island unable to escape by bridge, Loy said in his recently published oral history with the U.S. Naval Institute.

“As you remember, the footage of the day had this constant stream of people walking north and across the Brooklyn Bridge,” Loy said.

“And not so much understood were the people south of the towers who couldn’t go north and east to the Brooklyn Bridge. They went south and into the water, into the water frankly often literally so but more often in this unending stream of commandeered vessels that the Coast Guard directed to be taking people off Manhattan and taking them over either to New Jersey or Staten Island.”

A hodge-podge of area vessels were put into service — tugs, ferries, New York police and fire boats and private vessels — to evacate the southern tip of Manhtann, Loy said.

“The Staten Island Ferry, the Governors Island Ferry, the tour boat that runs around Manhattan became an ad hoc armada that off-loaded almost a half a million people to the water from South Manhattan,” Loy said.

The evacuation — in numbers — was, “bigger than Dunkirk,” referring to the 1940 World War II evacuation of 338,226 British, French and Belgian soldiers by mostly private vessels from France to the U.K.

“The direction was being provided by young Coast Guard officers from Staten Island that just happened to be on whatever platform they were standing on, kicking ass and taking names and directing traffic and pulling off this unbelievable debarkation from Manhattan,” Loy said.

In the days that followed the initial attack, Loy oversaw securing U.S. ports and restoring infrasturcture to allow commerce to come into the eastern part of the country.

“The real reality after I put out some direction was in the hands of commanders and captains who were the respective captains of the port and did what they needed to do, including all the stuff I told them to do and whatever else they felt was appropriate,” Loy said.

“If I am a Coast Guard commander locally, I don’t have to wait for my boss to tell me. I know what the hell I’m supposed to do in the middle of a nightmare that I’m capable of dealing with and I go do it.”

During the aftermath of the attack, Loy also directed then-Master Chief of the Coast Guard Vince Patton to assign a detail to remove debris from the Trinity Church in New York — final resting place of USCG founder Alexander Hamilton.

“I said, ‘Vince, I need you to get some senior enlisted folks from Captain of the Port of New York’s office. I know they’re up to their ass in alligators right now, but we’ve got to go fix that’,” Loy said.

“I was damned if I could go to sleep that night without doing something about it.”