"It showed how close the war was coming," said Dunn, 68, of Sea Girt, whose book proceeds will be used for the lighthouse's upkeep.
The Resor drifted for two days, then sank 31 miles off Barnegat. Other enemy incursions followed - with the landing of German saboteurs from a U-boat on Long Island, N.Y., and other enemy agents in Jacksonville, Fla., in spring 1942.
Their targets were major hydroelectric plants, aluminum factories, critical railroad tracks, bridges, and canals, along with the water-supply system of New York City.
But one of Nazi Germany's early successes - the sinking of the Resor - happened at the Jersey Shore, a vacation destination that suddenly found itself in the crosshairs of Hitler's war machine.
"I was a sophomore in high school at the time," said Walter Judge, a retired physician and local historian who lives in Spring Lake. "I remember the globs of oil all along the shoreline.
"The local public works crew dug a big hole and shoveled in the globs," he said.
Other U.S. ships were also torpedoed along the Shore in the months to come.
"What was apparent to locals through the war was that Allied ships were being sunk," Dunn said. "It became common for the boardwalks and people at their homes to have jugs of solvent to remove the oil and tar from feet and elsewhere."
In response to the enemy threat, a July 22, 1942, "order came from Coast Guard command to extinguish the light at Sea Girt Lighthouse and most other lighthouses, so as not to give navigational aid to the enemy ships," Dunn said. "Our ships navigated by LORAN," short for "LOng RAnge Navigation," a hyperbolic radio navigation system developed in the United States during World War II.
At the same time, the Coast Guard's manpower at the Sea Girt Lighthouse "increased steadily to staff watch duty in the tower and beach patrols," Dunn said. It rose from only a few when the war broke out to 18 in spring 1942 - then 21 by the fall and 28 by spring 1943.
One of the local youths, Donald Ferry - now a former trustee and former president of the Sea Girt Lighthouse Citizens Committee - befriended the Coasties during the war. He lived in a summer house adjoining the site.
"I was about 12 years old then," said Ferry, 85, of Sea Girt. "I knew all of them; they were friendly and knew me and my family.
"They patrolled the perimeter of the lighthouse property and used the brand names of cigarettes as passwords - Camel, Chesterfield, Lucky Strike," he said. "I'd cross their property [on the way to the beach], and they'd say, 'Halt! Who goes there?' "
The Coasties gave him the password, Ferry said, and he repeated it. "They'd say, 'Pass, friend,' and I'd go on," he recalled.
Coast Guard members from the lighthouse carried guns and flare pistols as they walked the Sea Girt beachfront from dusk to dawn; others from Spring Lake and Avon patrolled those towns.
"During the war, amazingly, vacationers still went to the beach, which was oily, as was the water, from the ships lost in local waters," Dunn said.
The oil "used to drive us crazy," said Ferry. "We'd use kerosene to wash it off."
By 1943, the brick lighthouse was painted brown to disguise it and help blend it in with other houses. It also was fitted with a dipole transmitter that produced a radar beacon for Allied vessels to navigate by.
The U.S. military remained on the alert along the Jersey Shore for German subs - and sank one off Point Pleasant in 1945. The wreck was discovered in 1991.
Today, the Sea Girt Lighthouse is a historic landmark, museum, and gathering place for local groups and community events. But more than 70 years ago, it stood like a sentry guarding the Shore.
"The Resor and other attacks had brought the war to America," said Dunn, a trustee of the Sea Girt Lighthouse Citizens Committee.
"It wasn't just in Europe and Asia anymore," he said. "It had come to our shores."