New London — The blast of a cannon boomed through downtown New London at 8:46 a.m. on Saturday, marking 20 years to the minute from when the first of two hijacked planes slammed into the World Trade Center towers on Sept. 11, 2001.

Crowds gathered under a bright blue, cloudless sky — a day not unlike the day tragedy struck 20 years ago — for a ceremony at City Pier in honor of all those who were lost in the unforgettable terrorist attacks that shook the nation to its core, leaving it forever changed. The ceremony marked the start of this weekend's Connecticut Maritime Heritage Festival.

The sounds of cannons jolted an otherwise quiet, peaceful morning several times, to mark the strike and fall of each tower; the downing of a plane in Pennsylvania; and the attack on the Pentagon, as scores of people bowed their heads in remembrance. First responders, members of the military, local legislators and civilians alike gather to mourn, remember and vow to never forget.

In a ceremony led by Capt. Todd Moore, Commanding Officer of the Naval Submarine Base New London, the solemn morning included prayers for first responders and military members still serving; moments of silence for the fallen; a presentation by the color guard; and the singing of the national anthem by the newly formed Eastern Connecticut City Singers group.

Moore paid tribute to the nearly 3,000 victims of the terrorist attacks, saying "the loss which at first seemed uncountable still seems unimaginable" and called 9/11 "a date that changed the world forever."

The captain recognized the heroism of American first responders and military members and New London's proximity to so much military history.

"We are surrounded by a legacy of boldness and courage," he said, gesturing to the city and Sound as he spoke.

U.S. Sen. Chris Murphy, who spoke at the ceremony, called New London "a city that is defined by America's commitment to protecting our nation, our shorelines; a commitment of service."

The senator referenced former president George W. Bush's speech the evening of the 9/11 attacks, in which he said acts of terrorism "cannot dent the steel of American resolve."

"American resolve exists right here in New London and Groton," said Murphy. "American resolve is the submarines that go out from these ports to defend America all around the world; American resolve is the Coast Guard Academy training a generation of leaders and protectors; American resolve is the City of New London, deciding year after year to bring people together in a diverse and inclusive community, and a loving community."

U.S. Rep. Joe Courtney, D-2nd District, said he was impressed, but not surprised, by the number of Southeastern Connecticut residents who attended the ceremony on Saturday.

"The turnout here this morning speaks so powerfully that the passage of time has not diminished the depth of emotion this area feels, still to this day," he said.

The congressman spoke of the residents from Southeastern Connecticut who were killed on 9/11 and those who volunteered to help in its aftermath. He also read the names of service members who were killed overseas after volunteering to protect the nation after 9/11.

"These are true patriots who took the road less traveled who stepped forward to make sure that we were going to bring justice to those awful events," he said.

The ceremony included the tolling of a bell eight times, a sea service tradition to mark a symbolic "end of watch," for all of those who were killed on 9/11. The New London Firefighters Pipes and Drums performed a rendition of "Amazing Grace" as Norwich Fire Boat Marine 1 launched an arch of water above the ceremony.

Navy District Fire Chief Tommy Clapsadle told the story of Thomas Butler, a 37-year-old firefighter with Squad 1 in Park Slope, Brooklyn, who was killed when the second tower collapsed. New London Fire Department Chief Thomas Curcio and New London Police Department Chief Brian Wright accepted an American flag presented to them during the ceremony as a tribute to the service and sacrifice of all first responders.

The ceremony included the retirement of an American flag that had flown aboard the USS Hartford submarine, by members of the Navy and American Heritage Girls Troop 003 based in Ledyard. The scouts, ranging from kindergarten age to high schoolers, were dressed in red and blue vests and sashes and each held small American flags in their hands as they participated in the ceremony.

Christine and Michael Giuliano of Waterford attended the ceremony with their 7-year-old son Matthew Giuliano and 2-year-old daughter Molly Giuliano. They hoped the event would help their children learn about the history of their nation.

Matthew Giuliano, carrying a book about fire boats and wearing a sweatshirt from retired FDNY fire boat Fire Fighter — which served the FDNY from 1938 to 2010 and was docked in New London last year — was there to learn about the historic event and the heroes who helped on 9/11.

"He's starting to learn about 9/11, and we want him to learn about the service and the sacrifice that so many people have given," said his mother. "We bought him a book to help him learn about it without scaring him, and I was quite happy to see how respectful he's been today. He understands when we tell him that these individuals (first responders and military members) are here to protect him."

While the Giuliano family hoped to teach their young children about a tragedy that happened before they were born, others attended the ceremony to remember a day that is seared into their memories forever.

David and Debbie Lawrence, who are in their 80s and met while attending high school in New London, remember the tragedy of 9/11 vividly and were proud to see their city honoring the fallen heroes.

"It was a wonderful and inspirational ceremony, especially in this period of time we're living in," said Debbie Lawrence, a former teacher. "It's so important to remember and to teach the younger people about what happened, you have to take the time to educate them and have them participate in things like this so they can understand."

David Lawrence said that he was impressed with the extensive ceremony, which spanned more than an hour Saturday morning.

"It helped me to realize the importance of our military presence here. I grew up here, so I've always been surrounded by it, but it's good to reaffirm that understanding and feeling of how important the military and our military history is," he said.

Eleanor Mariani, work group chair for Opsail CT events, said that Opsail, the U.S. Navy and the U.S. Coast Guard worked tirelessly for months to organize the memorial event.

She said Saturday's ceremony was "a beautiful tribute to those poor souls that passed on and also to the first responders that were there to respond in the aftermath of that" and a meaningful way to start the weekend's Connecticut Maritime Heritage Festival.

Honoring the anniversary, she said, was an important and honorable way to begin the annual festival.

"September 11th is an event that we don't want to forget and this is a respectful way to start the festival," said Mariani.

Saturday morning's ceremony concluded with a performance of God Bless America by the Eastern Connecticut singers and the Coast Guard Academy Glee Club.

t.hartz@theday.com