Once long ago, a submarine collided with a Coast Guard vessel and sank with great loss of life.

Trapped survivors hammered on the hull in Morse code as divers lumbered about, trying to save them before their oxygen ran out.

The submarine community of southeastern Connecticut held its breath as headlines screamed out daily developments in every paper across the country.

Then somehow, in the swirl of history, the incident mostly faded from our collective memory.

A new book by Connecticut author Joseph A. Williams rescues this tense drama from obscurity and brings it thrillingly alive. “Seventeen Fathoms Deep” recounts the story of the ill-fated S-4, which met its demise off Provincetown, Mass., in December 1927.

Despite having all the elements of a grand and tragic adventure, this tale has never before landed between the covers of a book. That’s at least partly because a trove of vital documents lay forgotten in an archive at the State University of New York Maritime College.

Williams, deputy director of the Greenwich Public Library, stumbled onto them while researching something else. They were in three boxes that appeared not to have been opened for decades.

Williams was the right man for the job of extracting from them a compelling, comprehensive narrative. His recreation of the S-4 disaster is absorbing, lucid and paced like a novel.

The submarine was on routine trials off Cape Cod when it surfaced in the path of the Coast Guard destroyer Paulding, on liquor-smuggling patrol during Prohibition. The S-4, its hull torn open, sank to the bottom.

Inrushing water and chlorine gas soon killed most of the 40-man crew. But six men in the torpedo room were sealed off by watertight doors. For the time being, they were safe.

The Navy sent an armada of rescue vessels, led by the Groton-based USS Falcon, a minesweeper fitted out for diving and salvage. But their progress was measured in hours and days rather than precious minutes as breathable air dwindled inside the sub.

No fiction writer would impose a howling, endless storm on what was already a logistical nightmare. But thats what happened, adding new layers of peril to delicate diving operations and bringing matters to a halt for days at a time.

The dives to the wrecked vessel are the heart of the drama, and they proceed with agonizing slowness as the clock ticks. Williams’ clear-eyed writing makes the divers’ complex movements easy to picture as they try to keep cumbersome lifelines from snagging on wreckage as they work.

From inside the S-4, messages tapped out by the survivors are haunting in their plaintive brevity.

“How long will you be?”

“Air is very bad.”

“Is there any hope?”

The S-4 incident occurred in the shadow of another submarine disaster closer to home. Two years earlier, in 1925, the Groton-based S-51 was struck by a merchant steamer off Block Island and sunk. All but three of the 36 on board were killed.

Many of the Navy officers who oversaw the salvage of that sub were on hand for the S-4 rescue, trying to apply what they had learned to a very different situation. They give the story a core group of interesting personalities.

There’s Edward Ellsberg, who raised the S-51 but left the Navy after he wasn’t promoted and his safety recommendations weren’t accepted. He predicted another disaster within two years. When he heard about the S-4, he raced to the scene to help.

There’s Tom Eadie, the master diver who, after decompressing from a dive, was summoned to go back underwater before he had safely recovered. Another diver was trapped and had to be rescued. Others were available, but Eadie was the best.

And there’s Ernest J. King, the blunt, arrogant former commander of the submarine base in Groton, who flashed his temper and made enemies but was also brilliant and ambitious. He went on to lead the U.S. Navy throughout World War II.

Some of the book’s best moments take place away from the rescue. Mining both official documents and newspaper stories, Williams has an eye for telling vignettes.

These include the two Coast Guardsmen at a remote Cape Cod lifesaving station who knew a submarine was in the vicinity and were looking for it with a telescope. By chance they became probably the only witnesses to the collision from ashore.

An enterprising reporter was in a unique position for a scoop. A former Navy man, he used the headlights of his car and semaphore to hail a ship in the distance. The ship responded, and he became the first to learn of the accident.

The mother of one of the S-4’s crewmen waited hours in the Providence train station for the expected arrival of the secretary of the Navy. When she confronted him, he gave her a ride to Provincetown but no good answers about her son’s chances.

The loss of the S-4 spurred advances in submarine rescue technology that saved the day 12 years later when the USS Squalus sank off the Maine-New Hampshire border.

A diving bell had been developed by Lt. Charles “Swede” Momsen and tested using the raised S-4, now an experimental vessel. In 1939 it brought all 33 survivors of the Squalus to safety in the greatest submarine rescue of them all.

This was the S-4’s legacy, and now its important story has finally received a worthy telling. “Seventeen Fathoms Deep” should take its place alongside “On the Bottom,” Ellsberg’s memoir of the S-51 salvage, and “The Terrible Hours,” Peter Maas’ recounting of the Squalus adventure.

The disaster also left a smaller legacy locally, though its origins are largely forgotten. The S-4 crewmen were well-known here, but the death of one young machinist’s mate caused particular grief because he was a New London native.

In 1928 friends petitioned the City Council for a permanent memorial. A place called Bullard’s Corners was renamed in his honor, and the name stuck.

The lost seaman was Arthur Frederick Hodges, and his name lives on in Hodges Square.

j.ruddy@theday.com

Twitter: @jruddy64