When Tom Joyce showed up for duty at Caven Point Army Depot near Jersey City on April 24, 1943, he was probably thinking this would be another routine day supervising carpenters working on board the El Estero ammunitions ship docked at the pier. The Coast Guardsman was probably thinking about how he and his fellow “Subway Sailors”—as land-based members of the Coast Guard had been dubbed by the longshoremen and ship workers who toiled around the same docks—would spend the upcoming Easter holiday in the city. He was probably thinking about what would be served for supper that night and how long it would take him to change into his dress blues afterwards.

Tom Joyce was probably not thinking that within a matter of hours, he would be fighting not only for his life, but the lives of everyone who lived in the city across the river. The story of how Joyce and a handful of volunteers were able to save New York City from what is now considered one of the greatest threats to an American city during World War II were featured in a 2015 episode of the podcast The Memory Palace.

Joyce was aboard the El Estero on anti-sabotage duty that day. After German agents had managed to ignite munitions stored on Black Tom Island in New York Harbor during World War I, what happened and what was stored at Caven Point Army Depot was a secret to everyone except members of the Coast Guard, the Marine Division of the FDNY, and the local Bayonne Fire Department.

The El Estero was one of many ammunitions ships that passed through Caven Point on the way to the fronts of World War II in Europe and Africa. On April 24, the ship was loaded with 1365 tons of explosives and was docked next to two other munitions ships. In total, 5000 tons of bombs, anti-aircraft, and small-arms ammunitions were being stored in close enough proximity that a fire on one ship would likely spread to the other two.

A fire on the El Estero broke out under the boiler room around 5:30 p.m. Somehow, possibly due to the fires that workers were building to create the steam needed to move the boat, a spark ignited the oily seawater. The fire spread quickly and blocked any access to the source of the flames. The best thing the Guardsmen could think to do was try to extinguish some of the flames with water to the point where the oil fire could be treated with chemicals.

If the ammunitions at Caven Point detonated, the blast would be similar to a modern nuclear weapon hitting New York Harbor, lower Manhattan, Brooklyn, Staten Island, and the fuel storage tanks that lined the shores of New Jersey. (If the Richter Scale had existed at the time, the explosion resulting from the Black Tom fire in 1916 would have measured 5.5. It had taken $100,000 to repair the Statue of Liberty afterward, and damage sustained by the torch in the blast permanently closed the interior ladder to visitors. And that was estimated to have been from 2000 tons of munitions. This explosion was looking to be over twice as big.)

When Joyce first saw the smoke, he calmly instructed the workers he had been supervising to pack up their tools and leave for the day. When all the carpenters were safely off the ship, Joyce grabbed a hose and an axe and began smashing in skylights and ceilings to make room for more hoses.

Volunteers from the barracks and local firefighters arrived. Guardsmen were put to work on the ship hauling hoses, moving railroad cars that were filled with explosives, and checking the temperature of the bombs on the ship by touch and then signaling for water if any felt warm. One Guardsman was given the task of feeling for hot spots on the deck. Despite directing water to wherever he felt heat through the floor, the fire continued to spread.

As the sun started to set, the orange glow on the dock was attracting attention, and a warning was sent out over the radio to residents of New York and New Jersey that an explosion was imminent. People were advised to take shelter indoors and away from windows.

After three hours of pouring water onto the burning ship, the fire still raged. Authorities had already dismissed the idea of sinking the boat where it was docked. The dock would lose valuable real estate. The only way to save the city seemed to be to ask for volunteers who would help move the flaming El Estero into the open harbor in order to minimize the effects of an explosion.

So many volunteered that officers had to assign some men to stay on the dock. As two tugboats began pulling the ship away from the pier, the soldiers on board tossed their wallets and watches back to those who remained behind. The body of any man who was still on board when the El Estero exploded would be unidentifiable.

The boat was pulled away from the dock, into 40-foot-deep water in another part of the harbor. For the next two hours, the Subway Sailors on board continued to pour water into the vessel in hopes that eventually the weight of the water would be strong enough to bring down the ship. Men began to pass out from exhaustion or smoke inhalation. Water began to lap onto the starboard deck, but the deck on the port side was so hot it sizzled shoes.

Eventually the call rang out: “Abandon ship!” and the El Estero sank. For the next several hours, fires would continue to burn on the exposed portions of the ship, but the threat of explosion was over.

Every man who had volunteered to fight the fire on the El Estero returned that night, though few returned from the fight unscathed, and one spent three weeks in the hospital dealing with the consequences of smoke inhalation and fatigue (not to mention a broken finger from saving a fireman). The city, and its residents, all survived. A few months later, Lieutenant Commanders John Stanley and Arthur Pfister received medals for their leadership that day. The full details of the incident weren’t released to the public until 1944. But for Tom Joyce and the Subway Sailors, the day ended with a return to the barracks, questions of what was for dinner, and hopes that the next time they reported for duty, the day would be more routine.