The Merchant Marine in World War II was supposed to just tool around the world's oceans, delivering supplies to ports and troops in Europe, Africa, and the Pacific while the real fighting was done by sailors, soldiers, and Marines. But due to German U-boats and other attackers, the mariners actually operated in an extremely dangerous niche.
A U-boat reloads new torpedoes during World War II.
One of the biggest dangers was of U-boat attack, when even a single boat could wipe out an entire convoy, provided that the boat was able to surface and attack using its deck gun.
The mariners were in danger from the moment they lost view of the land. U-boats would typically attack deep into the Atlantic, but they liked to remind Americans that they weren't safe at any time, so some U-boats were sent to hunt right off the coast.
Regardless of when the attack came, most merchant vessels didn't have any kind of sonar or radar, not even all Navy vessels had those detection systems in World War II. So, unless your ship was in a large convoy with a naval escort, you won't know a U-boat was there until it attacked.
When the U-boat attack got under way, it played out in one of two ways. If there were no threats of a U-boat in the area, you would find out you were under attack when a black hulk slowly surfaced in the nearby waves, a few sailors poured out of it, and the deck gun began firing on your ship.
These were often capable of sending 3.5-inch rounds into the hull of your thin-skinned cargo vessel, allowing water to pour into the lower decks and slowly send you deep into the sea. And since the attacking vessel is a tiny U-boat and not an enemy destroyer or cruiser, there's no way to get rescued. You have to paddle your lifeboats through a sea filling with oil from the sinking ship, potentially as it's on fire.
And, believe it or not, that's, by far, the preferred option.
That's because the other likely method of attack from a U-boat comes via its torpedo tubes, which means there's no surfacing ship, no scramble of sailors to warn you. You might, might notice a darkness in the water before a stream bubbles starts racing towards your ship.
If you look a few feet ahead of this stream of bubbles, you'll see the 21-inch diameter, almost-24-foot-long metal tube barreling towards your ship at nearly 35 mph. It will reach you. It will hit you. And its 600-pound (or heavier) warhead will rip apart the hull.
What happens next depends almost entirely on what cargo is being carried. Got a bunch of foodstuffs like grain and fruit? The boat will sink fairly slowly, and you'll have a chance to escape. But if you were carrying lots of heavy war materiel, like tanks and planes or, worse, industrial goods like iron and coal, you're pretty much screwed. The weight and density will take the ship down in minutes.
But the worst came when the ship was carrying fuel or oil. The massive explosion from the torpedo warhead would often rupture any tanks on the targeted vessel, providing a massive burst of heat as the pressure wave mixed the targeted fuel with the outside air, virtually guaranteeing massive fireballs and explosions as the torpedo exploded.
The Allied tanker Dixie Arrow sinks after being torpedoed in the Atlantic Ocean by a German submarine.
When you're on a tanker and the tanks suddenly explode, there's not a lot to be done. The steel around you has likely been twisted, the decks are burning hot and searing your flesh, and the blast wave has likely scrambled your brain. If you're lucky enough to survive, you now have to overcome your scrambled brains, make it through the burning corridors, and then try to get in a boat and get away from the deck before the suction takes you under.
If you did make it out of a shipping ship, your ordeal isn't over. Traditionally, combat ships would rescue survivors from enemy vessels once hostilities were over. If a cruiser sinks a destroyer, then once the destroyer crew surrenders the cruiser crew would begin taking on the survivors and would later take them to POW camps.
But U-boats barely have enough room for the crews. They can't take on survivors. So, after sinking anything from a fishing trawler to a destroyer to a passenger ship, the U-boat crew typically can't do much more than offer some loaves of bread or water before sailing away. They wouldn't even tell other Allied ships where to pick up the survivors, at least not at first, since that would give away the location of the subs.
Surrender of German U-boat, U-858, 700 miles off the New England Coast to two destroyer escorts, May 10, 1945.
Even if your ship was in a convoy, there was no guarantee that you could be picked up by friendly ships since a U-boat wolf pack could sink the entire convoy, leaving dozens of life boats in its wake, filled with slowly dying soldiers desperate for water or food.
To add insult to injury, Merchant Marine members were rarely paid for any period where they weren't actively crewing a ship, and no, lifeboats don't count. So their harrowing trial to survive at sea is performed for free, solely for the hope that they'll survive.
And throughout all of this, the U.S. would often keep the sinkings of ships secret, reporting just a couple of ship losses every week while dozens might have gone down.
Luckily for mariners, British innovation and American industry eventually gave the sub hunters the edge over the submarines, culminating in "Black May" 1943 when German losses got so steep that subs essentially withdrew from the Atlantic, allowing the Merchant Marine to finally sail largely in peace.