Back when I was a kid, unknowingly lucky enough to be regularly wandering around a fabulous small-town library like the Oregon Public Library, one of the youth history books that I read about World War II (and there was an industry of such publishing in the 1950s and 60s) was focused on the exploits of the Coast Guard, and their now largely-forgotten contribution as Nazi U-boats sank an astonishing amount of shipping within sight of our coasts. So I was struck to see this New York Times article/obituary call one of those stories to light.
In the spring of 1942, Seaman John Cullen was assigned to one of the Coast Guard’s less glamorous tasks in an America newly at war.
Seaman Cullen was a “sand pounder,” the term for Coast Guardsmen who patrolled beaches looking for signs of lurking German submarines or perhaps someone or something suspicious on the sand.
“Once in a while you might run into somebody, but very rare,” Mr. Cullen, who died on Monday, told a Coast Guard oral history interviewer in 2006, recalling his patrols on the eastern Long Island shore near his station at Amagansett.
On Friday the 13th of June ’42, Seaman Cullen was on patrol about a half-hour past midnight when it was “so foggy that I couldn’t see my shoes.”
He spotted a figure in the mist and the outlines of three others behind him. “Who are you?” he called out, shining his flashlight at the group, his Coast Guard insignia visible.
The man closest to him said that he and his companions were fishermen who had run aground. He spoke English well enough, but one of the others, dragging a bag, shouted something in German.
Seaman Cullen was “armed” only with a flare gun for sending signals when he came across what he figured were surely German spies. Moments later, he fled from the men and ran back to his station to sound an alarm. He led fellow Coast Guardsmen to the spot where he had encountered the four. They were long gone, but the Coast Guard dug up explosives they had buried.
Thus began a hunt for saboteurs who had been sent to the United States on U-boats by the German military spy service in a plot to blow up rail facilities and war-industry plants.
Eight men — the four who landed on Long Island and another four who arrived in Florida — were arrested before any sabotage could be carried out, and Seaman Cullen became a hero.
Mr. Cullen, who was 90, died of congestive heart failure in Chesapeake, Va., his daughter, Jean McLaughlin, said. He had retired there with his wife, Alice, in the early 1990s after working as a dairy company sales representative on Long Island and living there in Westbury.
John Cornelius Cullen was born on Oct. 2, 1920, in Manhattan, but grew up in Queens. He enlisted in the Coast Guard a few weeks after the Japanese attack on Pearl Harbor.
A few minutes after he discovered the supposed fishermen on that foggy night in June ’42, the leader of the group, dropping all pretence, asked Seaman Cullen if he had a mother and father who would presumably grieve for him. The man did not display a weapon but said, “I wouldn’t want to have to kill you.”
But then the tone changed. The man offered Seaman Cullen what he said was $300 in American money, saying, “Why don’t you forget the whole thing?” Seeing a chance to escape, Seaman Cullen took the money, promised he would never identify the men and ran back to get help. (He then found he was shortchanged; he had been given $260.)
The four German agents, minus their explosives, took the Long Island Rail Road into Manhattan that morning, arriving at Pennsylvania Station. A week later, the group’s leader, George Dasch, shaken by his encounter with Seaman Cullen, traveled to Washington and surrendered to the F.B.I., hoping he would be regarded as a hero in America by exposing the plot.
That led to the roundup of his fellow conspirators in Operation Pastorius, named for Franz Pastorius, who in 1683 led the first German settlement in America.
At a secret military trial in Washington, Seaman Cullen identified Mr. Dasch as the man he had encountered on the beach. Six of the eight saboteurs were executed on Aug. 8, 1942. Mr. Dasch and another conspirator who cooperated were given prison terms and deported to West Germany after World War II.
Seaman Cullen became enveloped in the Coast Guard’s publicity machine. He was brought to news conferences to tell of his adventure; appeared at parades, ship launchings and war-bond drives; and received the Legion of Merit. He remained stateside throughout the war as a driver for high-ranking Coast Guard officers, then left military service.
In addition to his daughter, Seaman Cullen is survived by his wife, Alice; a son, Wayne; his sisters, May Donnelly and Edna Beaver; five grandchildren; and six great-grandchildren.
During the hullaballoo over the spy story, a personnel employee at Macy’s in Herald Square who had hired Mr. Cullen as a deliveryman’s helper before his Coast Guard enlistment described him to The New Yorker as “a thoroughly wholesome, typically American boy” with “a modest demeanor.”
Seaman Cullen played down the hero angle when he appeared at a Coast Guard news conference in 1942. “The German fellow was nervous,” he said, “but I think I was more nervous.”
A version of this article appeared in print on September 3, 2011, on page B8 of the New York edition with the headline: John Cullen, 90, Coast Guardsman Who Detected Spies.