The military and a private organization are bringing home the remains of 36 Marines killed in one of World War II's bloodiest battles.

The U.S. Marine Corps says a Florida-based private organization called History Flight recovered the remains from the remote Pacific atoll of Tarawa. A ceremony is being held Sunday in Pearl Harbor to mark their return.

History Flight has started identifying the remains, and the Defense POW/MIA Accounting Agency will complete the effort.

The Marines will return the remains to their families after they've been identified.

About 520 U.S. servicemen who served in the Battle of Tarawa in 1943 are still unaccounted for.

The three-day battle taught the Marines lessons about amphibious landings that they went on to use in the war against Japan.