Forensic anthropologist Gregory Fox and his team sifted dirt on the remote Pacific atoll of Tarawa at what they thought might be graves of U.S. Marines and sailors killed in one of World War II’s most savage battles.

They unearthed instead a mass grave of Japanese soldiers killed in the 1943 battle, along with a forgotten local cemetery.

The Honolulu-based Joint POW/MIA Accounting Command team searched four other sites during a recent six-week trip to Tarawa in hopes of finding the remains of a couple hundred U.S. servicemen. But they came up empty each time, underscoring the difficulty of bringing home those missing from America’s wars.

The team returned to their Hawaii headquarters with the remains of two individuals, but they had been found earlier by a local citizen.

The discovery of the Japanese remains, however, provided a vivid and poignant reminder of the ferocity of the long-ago battle.

The remains were buried in an artillery shell crater, along with Japanese military equipment from the era. Photographs of the skeletons were sent to the team’s Hawaii lab, which verified that they were Asian.

The team cleaned and bagged the Japanese remains they excavated and handed them over to the Kiribati government, which is expected to repatriate them to Japan. It also refilled the graves and noted their location on a map in the event that Japan decides to recover the site.

Some 560 U.S. servicemen are unaccounted from the Tarawa battle. There are still 78,000 U.S. troops missing from World War II alone, including 35,000 the military believes it can recover. The rest are entombed on sunken ships or otherwise lost at sea. Thousands more are missing from the Korean and Vietnam wars.

"It would have been great, fantastic, wonderful to bring back lots and lots of remains," said Gregory Fox, a forensic anthropologist and archaeologist who led the excavation team in Tarawa.

But he said he wasn’t disappointed, noting the military has the remains of two more individuals than it had before. His team also laid the foundation for future missions to the small tropical atoll halfway between Hawaii and Australia that’s now the capital of the Pacific island nation of Kiribati.

"We’re very persistent," Fox said. "When there’s opportunities to recover missing U.S. service members, identify them and return them to their families, JPAC does everything in their power to make sure that we get there in a timely manner with the right teams, with the right scientific staff, to recover those remains."

Scientists in Hawaii are due to analyze the two sets of remains — potentially using DNA analysis — to identify them, a process that could take months or years.

More than 990 U.S. Marines and 30 sailors died during the three-day battle. Japanese machine-gun fire killed scores of Marines when their boats got stuck on the reef at low tide during the U.S. amphibious assault. Americans who made it to the beach faced brutal hand-to-hand combat.

Only 17 of the 3,500 Japanese troops survived. Of 1,200 Korean slave laborers on the island, just 129 lived.

The U.S. quickly buried the thousands of dead on the tiny atoll. But the graves were soon disturbed as the Navy urgently built a landing strip to prepare for an attack on the next Pacific island on their path to Tokyo.

"The Navy pretty much bulldozed it flat," Fox said. "A lot of these graves were obliterated as early as a month or so after the battle."