The city of Tucson donated 80 silver goblets bearing the raiders’ names when it hosted their 1959 reunion, with the names of each airman engraved both right side up and upside down. At each gathering thereafter, the survivors turned down the goblets representing their fellow airmen who had died since the previous reunion — though their names, having been duplicated, remained right side up — and they toasted all the departed.

The raiders had planned to hold annual public reunions until only two remained, when they were to uncork a bottle of cognac — vintage 1896, the year of Doolittle’s birth — for a private final toast.

But early in 2013, they announced that their last public reunion would be held that April at Fort Walton Beach, Fla., where they had trained, and that they would have a final, private reunion later in the year, no matter how many raiders were left.

As a centerpiece of the Florida reunion, Mr. Cole flew a restored B-25 Mitchell bomber, alternating at the controls with the plane’s owner, Larry Kelley, during a 40-minute flight over Florida.

“I kept looking over the altimeter,” Mr. Kelley told The Associated Press afterward. “I told him to hold 1,500 feet, and I kept looking at the altimeter, and it was dead on: not 1,499 feet, not 1,501 feet. He had the altimeter pegged at 1,500 feet.”

Mr. Cole made a fine landing, then stuck his head out the cockpit window and told reporters: “It’s the same as it was then. All I did was prove how rusty I am.”

When the remaining raiders held their final reunion in November 2013 — an invitation-only event attended by more than 600, including family members and descendants of the men on the mission and the Chinese villagers who aided them — Mr. Cole was joined by Edward J. Saylor and David J. Thatcher, who were engineer-gunners on the raid. The fourth surviving raider, Robert Hite, a co-pilot who had been captured by the Japanese, was unable to attend because of health issues. All were in their 90s. (Mr. Saylor and Mr. Hite died in 2015 and Mr. Thatcher in 2016.)