Robert D. Maxwell was an Army technician fifth grade when he was awarded the Medal of Honor for his actions during World War II. (Congressional Medal of Honor Society)

He heard the hand grenade land but could not see it. And as the seconds ticked away and Robert D. Maxwell searched blindly through the darkness, he decided that the only thing worse than running away was picking up the explosive device and trying to throw it back at the enemy — an act that risked killing the three soldiers crouched alongside him.

When he finally found the grenade, lying on the cement courtyard outside his battalion’s embattled observation post in eastern France, he did the only thing that made sense. Clutching a blanket to his chest, he dropped on top of the device, absorbing the full force of its explosion and saving the lives of his comrades.

“It’s not the case that I was brave or a hero or anything like that,” Mr. Maxwell, an Army technician fifth grade during World War II, said years later. “Because I just did what the only alternative was at the time. There was nothing else to do.”

For his actions early that morning on Sept. 7, 1944, Mr. Maxwell was awarded the Medal of Honor, the nation’s highest military decoration for valor. He was 98 and the oldest surviving Medal of Honor recipient when he died May 11 in Bend, Ore., leaving only three surviving recipients from World War II.

His death was announced by the Medal of Honor Society, which did not say precisely where or how he died.

Mr. Maxwell had seen action long before his unit came under fire in France. A onetime Colorado timber worker, he served as a “wire man,” scaling roofs or trees to hang phone lines that enabled his battalion to communicate quickly on the battlefield.

Mr. Maxwell, in 2017, places a wreath in front of a U.S. Army flag at a church in Bend, Ore. (Ryan Brennecke/Bulletin/AP)

He carried an M1 rifle in North Africa before being reclassified as a noncombatant — with his wires and tools, the load was considered too heavy — and given a .45-caliber pistol for the invasions of Sicily and mainland Italy.

In Anzio, where Allied forces secured a beachhead for the liberation of Rome, Mr. Maxwell took shrapnel in both legs while repairing communications wires. He was hospitalized for several months in 1944 before rejoining his unit, the 7th Regiment of the 3rd Infantry Division, for an invasion of southern France dubbed Operation Dragoon.

By September, Mr. Maxwell’s battalion had reached the city of Besancon, near the Swiss border. He was stationed with a few G.I.s at an old, pockmarked farmhouse on the outskirts of town, stringing wire on the roof of the observation post, when a German platoon suddenly opened fire with machine guns and 20mm antiaircraft weapons.

As bullets sheared tiles from the roof, Mr. Maxwell leaped to the ground, taking shelter behind a short rock wall topped with a wire-mesh fence. The German forces had apparently outmaneuvered American rifle companies nearby, coming within 10 yards of the wall and nearly as close to Mr. Maxwell’s battalion commander, Lt. Col. Lloyd B. Ramsey, who was inside the post with other officers.

Mr. Maxwell and his three comrades marshaled a defense, armed only with their .45s.

“Maxwell’s courage was what held us together,” Cyril F. McColl, a technician fourth grade, later told Collier’s magazine. “The machine-gun fire was just clearing his head, but he sat there taking pot shots at everything that moved. Our wall was beginning to crumble, and I was thinking how nice it would be to get out of there, when a grenade came over the chicken wire, and hit the cement floor right at our feet.”

It was about 2 a.m. when Mr. Maxwell fell on the grenade and lost consciousness in the explosion that followed. By most accounts, when he regained consciousness, the post was deserted; his fellow soldiers, apparently thinking he had died, had evacuated the position as ordered. Mr. Maxwell staggered into the house, where he found the last man remaining, a lieutenant, gathering phone wire.

“I draped an arm over his shoulder, bled all over him, and we left,” Mr. Maxwell said in an interview for the book “Medal of Honor: Portraits of Valor Beyond the Call of Duty.” A jeep picked them up and ferried them to an aid station, where Mr. Maxwell received treatment as artillery fire obliterated the farmhouse and courtyard.

The grenade had wounded his right foot, torn his left biceps and struck his left temple near the eye. But although Mr. Maxwell was “permanently maimed,” according to his Medal of Honor citation, his actions “saved the lives of his comrades in arms and facilitated maintenance of vital military communications during the temporary withdrawal of the battalion’s forward headquarters.”

Mr. Maxwell was presented with the Medal of Honor in May 1945 while convalescing at Camp Carson in Colorado. Days earlier, his former commander, Ramsey, had helped lead the 3rd Infantry into Austria, where elements of the division liberated Salzburg and Berchtesgaden and pressed toward the Eagle’s Nest, Hitler’s mountaintop retreat.

“My apologies,” Mr. Maxwell told Ramsey at a 2010 reunion, “for having to leave you after Besancon.”

Robert Dale Maxwell was born in Boise, Idaho, on Oct. 26, 1920. Raised by his grandparents in western Kansas, Bob, as he was known, left school as a young man to work on their farm. He received a high school diploma only in 2011, at age 90.

Although he had a Quaker upbringing, Mr. Maxwell decided against becoming a conscientious objector and enlisted in the Army in 1942. He received two Silver Stars, a Bronze Star Medal and two Purple Hearts and after the war taught auto mechanics at high schools and community colleges in central Oregon.

Complete information about survivors was not immediately available.

“I’m not wearing the medal for any personal deeds,” Mr. Maxwell insisted in the “Medal of Honor” interview. “I’m wearing it because it represents all the casualties that we had in the war. It represents those who were killed defending their country and of the ideals that they believed in.”

Robert D Maxwell