Thirty-six American flag-draped caskets carrying fallen Marines from the Battle of Tarawa — including Medal of Honor recipient 1st Lt. Alexander Bonnyman Jr. — will arrive in Hawaii on Sunday for formal identification and return to their families.

“I was very pleased to learn of the discovery of the remains of our Marines on the island of Tarawa — one of our most significant and contested battles” of the Pacific campaign in World War II, Marine Corps Commandant Gen. Joseph Dunford said in a news release.

History Flight Inc., a Florida nonprofit that has been to Tarawa dozens of times in search of still-missing Marines, announced in June that it had discovered a long-lost burial trench on Betio Island on Tarawa Atoll that was the hasty grave site of at least three dozen Marines killed in fighting Nov. 20-23, 1943.

Among them was Bonnyman, initially identified while he was still in the sandy soil by his unique patchwork of gold fillings and crowns, which were compared against his dental record.

Two Marine Corps C-130 aircraft will fly the remains from Tarawa, now part of the Republic of Kiribati, to Kwajalein to Hawaii, where Marine pallbearers will turn them over to the Defense POW/MIA Accounting Agency for final identification in what’s known as a “dignified transfer.”

Eight teams of pallbearers are expected to carry four sets of remains at a time off the aircraft and bring them to a hangar at Joint Base Pearl Harbor-Hickam.

“It’s important to us because Marines take care of their own. We owe it to these guys,” said Chuck Little, a spokesman for Marine Corps Forces Pacific.

DPAA, with the bulk of its operations at Hickam, recovers and identifies missing American war dead.

Tarawa was the second offensive of the Pacific after Guadalcanal, and the amphibious landing faced a stiff and fortified Japanese resistance, with more than 1,000 Marines killed.

Before the 1943 attack, a Japanese admiral had bragged that “a million Americans couldn’t take Tarawa in 100 years.” The island was the most heavily defended atoll to be invaded in the Pacific.

According to his Medal of Honor citation, Bonnyman was executive officer of the 2nd Battalion Shore party, with the 8th Marines, 2nd Marine Division. The first lieutenant led his men off Betio Pier under heavy shore battery fire to the beach.

The following day he voluntarily crawled 40 yards past U.S. lines and placed explosives in the entrance of a fortified and “bombproof” Japanese bunker.

He then returned to lead his men against the bunker and directed the placement of more explosives. More than 100 Japanese were killed in the attack, the citation states.

Bonnyman made a “heroic stand” on the edge of the bunker and killed three more of the enemy before he was mortally wounded.

The Defense Department previously said about 520 U.S. servicemen remained unaccounted for on Tarawa. In the immediate aftermath of the battle, U.S. troops were buried in a number of poorly marked cemeteries. Navy combat engineers — Seabees — significantly restructured the landscape to convert Tarawa for use in the island-hopping campaign.

In 1946, when U.S. Army Graves Registration Service Personnel attempted to locate the battlefield interments, many could not be found, according to the Defense Department. Among the graves the registration unit was unable to find was “Cemetery 27,” and the men buried there were declared “unrecoverable” in 1949, History Flight said.

The organization said it eventually located the cemetery, and in it, the complete remains of Bonnyman, one of four recipients of the Medal of Honor from the battle, and the only one whose remains were unaccounted for.

Clay Bonnyman Evans, the Marine’s grandson, was there on Tarawa when his grandfather’s body was uncovered — revealing all the gold fillings that helped make a preliminary and then positive identification, History Flight said.

Evans allowed the release of photos and video of his grandfather’s recovery, the organization said.

“The location of Cemetery 27 has been one of Tarawa’s most challenging historical puzzles. History Flight’s discovery and recovery of the site is a testament to the tenacity and professionalism with which it has searched for all the missing Tarawa Marines,” Evans, of Niwot, Colo., said in the History Flight release.

The group, led by founder and director Mark Noah, is one of several the Defense Department has worked with in the past and might work with in the future under a more formalized agreement to recover missing war dead.

“We are very grateful for the efforts of Mark Noah and History Flight for the recovery of these Marines lost during the Battle of Tarawa,” said retired Lt. Gen. Michael Linnington, director of DPAA.

Linnington said DPAA’s lab at Hickam would “expeditiously confirm or complete the identities of the recovered Marines.”

Ed Huffine, board secretary for History Flight, said in the release that “although we have dental matches to known missing Tarawa Marines for more than half of the recovered individuals, we are seeking DNA reference samples from families of the Tarawa missing.”

He added that “we plan to have all of these recovered heroes identified by the end of the summer.”