Those to be remembered are Marine Sergeant Andrew K. Farrar Jr. of Weymouth, who died on his 31st birthday on Jan. 28, 2005; Marine Lance Corporal Walter K. O’Haire of Rockland, who was killed in action May 9, 2007, six days short of his 21st birthday; and 21-year-old Army Specialist Matthew M. Pollini, also of Rockland, who was killed in action on Jan. 22, 2009. Each will have an engraved stone affixed in a small garden, part of a series of individual pocket parks spaced along the greenway of SouthField, a new 1,400-acre residential community rising on the grounds of the former military installation.

The ceremony no doubt will be one of many across the region this weekend honoring men and women of all generations who have served in the military, as well as all who have lost their lives. But the rite at SouthField, in particular, is twofold: It aims to honor those three fallen sons with roots in the tri-town area of Abington, Rockland, and Weymouth who have died in the years following the Sept. 11, 2001, terrorist attacks, while also paying tribute to the new development’s military past.

Saturday’s program, which includes the monument dedications as well as remarks by local, state, and military officials, will feature two Marine CH53 helicopters performing a military flyover.

Kevin R. Donovan, chief executive officer of South Shore Tri-Town Development Corp., which is repurposing the old base, worked with veterans agents in Rockland and Weymouth on the memorial plan, which also includes naming streets in the development for deceased veterans from the three towns. He is encouraging the public to attend the ceremony to show support for the first three monuments to veterans who gave their lives for freedom.

“This is something I have always wanted to do,’’ Donovan said in an interview. “We had the ability to recognize the service these young kids gave so people don’t forget them, while giving some comfort to their families.”

And it is a comfort, said Andrew Farrar Sr., whose son, a husband and father of two, has been gone for seven years now.

“You think about what is required to maintain the lifestyle that we have, what freedom is all about, and the fact that 1 percent of the population enlists to do the work for the rest of us,’’ Farrar said. “It’s an obligation every American has, to give some time every day, to remember.”

Farrar flies a Gold Star flag at his Weymouth home to signify a fallen soldier, and he says people often stop to knock on the door to express their thanks for his son’s service.

“That gives me a little bit of faith in our society,’’ he said.

Farrar Jr., the oldest of four children and a 1992 Weymouth High School graduate, died after accidentally stepping on live electrical wires during a search for Iraqi insurgents. He had just broken his hand and had the chance to return to lighter duty while assigned to the Headquarters and Service Battalion, 2d Force Service Support Group, II Marine Expeditionary Force, but he declined, officials said.

At the time, he was scheduled to return home in three weeks. In 2001, Farrar had been planning to return to civilian life for a career in law enforcement when the Sept. 11 terrorist attacks inspired him to reenlist and head to his second tour of duty in Iraq.

O’Haire, known as Gator, after the popular 1970s-era Wally Gator cartoon, was one of nine children. He was born in South Boston but had lived in Rockland for 10 years. A soldier in the 2d Battalion, 6th Marine Regiment, 2d Marine Division, II Marine Expeditionary Force, he died in Al Anbar province when he came under enemy fire while patrolling with his platoon. He had only been in Iraq a little more than two months.

His mother, Maureen O’Haire, said she nicknamed her son Gator because, like the cartoon character, he was high-energy and couldn’t keep still.

“Gator was one of a kind,’’ she said. “We were very blessed. They just don’t make them like him.’’

O’Haire said her son was determined to serve his country because he wanted to make a difference.

“He told me he’d be home for his birthday,’’ she said. “And he was. Just not the way we imagined it.’’