World War One saw widespread attacks on merchant ships, and German U-boat submarines caused extensive losses to Allied shipping. This account reviews a dangerous 1917 trans-Atlantic crossing by the U.S. freighter Vigo, with Dale Clemons, a Marconi Wireless employee, acting as the ship's sole radio operator. In addition to long hours, the job of shipboard radio operator during wartime was especially hazardous. When a ship was attacked, one goal was to cut off its communications, so the first target was often the radio shack and its occupants.
Wake of the Wirelessman, Bette J. Clemons, 1991, pages 81-84:

    On returning to his cabin Dale stopped short. The door to the radio shack was standing wide open. He was greeted by a scowling officer of the US Navy who pointed to the door key and said, "Never leave this room unlocked!"
    "Yes sir," Dale answered, wondering if he was expected to salute. The officer sat down at the radio table and opened a briefcase, then began removing books and papers.
    Easing himself onto the edge of the bunk, Dale listened as the officer expressed the Navy's gratitude to the many Marconi operators who had volunteered their services. Then he explained the strict control Capt. Ryan hinted at earlier.
    "The US Navy has taken over all radio operation. Quite frankly, Mr. Clemons, if we had enough radio operators of our own you wouldn't be permitted here. But we don't and we need your experience." Then came the disheartening news.
    "Radio silence is the cardinal rule. No transmission is permitted unless your ship is in danger of sinking."
    The Navy man went on. Radio silence applied even when the wirelessman heard an SOS call. "Your captain is under strict orders to keep moving."
    "And let men drown?"
    "Navy ships are conducting all rescue operations now. It's no longer your concern."
    "Wait a minute. Why do you think I volunteered?"
    "Forget what you used to do. The fact is, you're more valuable than ever. Wireless is the only advantage we have."
    How could that be? he wondered. His thoughts were still on radio silence.
    "What do you know about the radio direction finder?"
    "Just what I learned in school. I understand the principle. Know there are several designs, none of 'em accurate."
    "That used to be true. What I'm about to say is highly secret and must remain so.
    "Engineers of the British Marconi Company have developed a system of pinpointing the position of a ship by receiving its radio signal. As for range, their new direction finder pretty well blankets the war zone. But the Germans don't know about it. Their submarine commanders use wireless, freely communicating with headquarters, thus giving away their exact location. Your job, Mr. Clemons, is to listen. The intelligence information on enemy location is transmitted every night during the regular midnight press broadcast. You'll be told locations of sinkings followed by what we're calling enemy sightings. Mark the locations on a map for your captain."
    "Does he know about this?"
    "He knows to expect reliable radio reports of enemy location."
    The captain and I will maintain a chart here in the wireless cabin, on which we will show by colored pins the positions of enemy craft and sinkings as these are reported. Already there are two pins up off Newfoundland and one in the south Atlantic, the latter for the raider Seeadler, even before we are at sea.
    He flipped to a page of the manual and handed it to Dale.
    "Memorize the new SOS procedure. Include what happened -- use abbreviations for torpedo, gunfire, mine explosion. Also, identify your attacker such as U-boat or surface raider."
    "Who will respond?"
    "Good question. Depends where you are. The nearest shore station will acknowledge and dispatch a destroyer, British most likely, could be French or Italian. No matter. We all use English in our messages."
    He closed the book. "Now comes the most important change. When in the war zone, you'll receive fresh reports of enemy locations. We have boats, disguised as fishing trawlers, patrolling the region watching for submarines and warning merchant ships of their presence. They use a special code word coined for this exact purpose, 'ALLO.' You'll then hear a sighting location: a town name, cape or the nearest point of land. Alert your captain so he can alter course."
    "What if we sight a submarine?"
    "Maintain radio silence!" the officer answered firmly. "The penalty for breaking radio silence is a fine of $25,000 plus a jail sentence and permanent revocation of your operator's license."
    Dale gulped. "Sir, I have to test this transmitter on full power."
    "Use a dummy antenna. No signals, not even in port. We don't know how good the German direction finder is but we're using ours to shut down amateur stations. We have to, some are in enemy hands."
    He handed the book and some papers to Dale for study. "Any questions?"
    "How can one man handle this job?"
    "Set up a work schedule. Sleep when you can."
    As the officer packed his briefcase he lapsed into casual conversation. "Ever wonder what shape we would be in without Marconi? I s'pose you know he barely missed being aboard the Lusitania when she was torpedoed."
    "Scuttlebutt has it the Germans were aiming to kill him. Now he's out there again, headed back to his homeland to join in the fighting."
    "We're going to Italy."
    "I know." The Navy officer snapped his briefcase shut and stood to leave, hand extended, "Good luck to you, Mr. Clemons."
Pages 141-147:

    The Vigo had traveled 3,000 miles from New York and Dale had gained a new friend -- Marconi's trans-Atlantic station Poldhu at Cornwall, England. It was easy to recognize not just by the call letters but by the tonal quality of the transmitter -- a smooth, low-pitched sound with signals emitted by the sender at a sedate pace befitting the station's renowned stature. It was there in 1901 that Marconi's experimental letter "S" was transmitted across the Atlantic, demonstrating the potential of wireless radio. Dale had studied so much about radio he could almost picture the original Marconi transmitter, a cluster of masts erected on a bleak rocky outreach, defying the ravages of nature like a lighthouse dedicated to mariner safety. And here he was, not very many years after it started, able to choose at will from numerous powerful transmitters on land beaming messages from every country in Europe, turned rivals by the war and reduced to deception. Telefunken, Marconi's rival, built Nauen (call sign POZ), the government station in Berlin now being used for propaganda. Daily, Paris contradicted Berlin's version of who was winning the war. He found himself hanging on every utterance from Poldhu. Surely they would tell the truth.
    When not tuned in to scheduled broadcasts, Dale scanned the dial listening to marine wireless traffic. The airwaves were increasingly cluttered. Even so, he was able to single out individual transmitters. Each set had its own tonal quality and the sender added his personal touch to the key -- his "fist" -- making the station as recognizable as a familiar voice in a crowd of people talking. Cape Race, Newfoundland (call sign VCE) suggested fog and had a bleak icy quality. FFU, the station at France's westernmost point, sounded like a bleating sheep. On the other hand, Monsanto, Portugal came in with a cheery, sunny, musical sound. And in sharp contrast, a German Telefunken quenched gap transmitter emitted a shrill signal. These features helped Dale focus his search for valuable information. Before long he made an important discovery. He reported to the captain by telephone, "Sir, submarines may be getting help locating our ships."
    "What makes you think that?"
    "Just now I heard someone report a location. No preamble, just a location."
    "So what?"
    "A marine Telefunken acknowledged. That means it's a German."
    "Sounds like you're on to something. Keep me posted."
May 30          6 AM. Crossed 7.5° west.
1,000 miles from Azs. 100 miles to Gbr.
Clock changed.
We're on GMT.
    Notation entered, Dale sat back and proceeded as usual to scan the dial listening for marine traffic. His heart jumped. He heard, ". _   . _ . .   . _ . .   _ _ _," (ALLO) followed by a profusion of dashes in a triplet pattern -- a warning as attention getting as SOS. He waited for the location. It came, "Cape Spartel." Dale phoned the bridge. "Submarine in our front yard, Cape Spartel."
    "Which side?"
    "Didn't say."
    He'd barely hung up the phone when it rang. Captain Ryan's voice sounded strained, "I want to check chronometers again before we enter the Strait. When can you get me a time signal?"
    "Paris gives signals hourly."
    "Set it up. We'll soon have our headland, Cape Spartel in sight."
    "Yes, sir."
    At 3:55 PM the phone rang again. "We're ready for clock check."
    "I have Paris. Counting down. Minus 5 seconds. Start, NOW!"
    Eyes closed, Dale concentrated on the monotone rhythmic sound of the time signal. Beep, beep -- the clock's tick counted down the seconds of the final minute. Suddenly he felt a sharp jolt and heard a dull thud. "What was that?" No answer. He rushed on deck, phone cords trailing. The British freighter just behind the Vigo had been hit. Heeled to one side, she was falling back, her bow enveloped in black smoke, a huge column of spray descending.
    Torpedoed! Everyone was shouting, running. The Vigo's whistle was blaring. Transfixed, Dale watched the wounded freighter begin to right herself.
    First glance at the ship astern showed her entire fore part enshrouded in smoke with a huge column of smoke and spray coming down over her. She had heeled over to starboard and was just swinging back to an even keel. Her engines had stopped and she was turning slowly toward her attacker. Her single gun was banging away at a tiny whitish feather far off and which disappeared in a few seconds. Our old ship was turning off to starboard . . .
    Baxter yelled at him, "Get back where you belong."
    Her funnel belching black smoke, the Vigo picked up speed, fleeing for her life. Following the prearranged plan, the convoy scattered. Dale thought, Rules or no, it's inhumane to leave the crew of a sinking ship to fend for themselves. But there was nothing he could do but listen.
    Returning to his desk he switched to the 600 meter wave length in time to hear the freighter's wireless open up with "SOS Knowsley Hall torpedoed [the cipher jumbled somewhat], position Lat. 35.40N Lon. 6.10W." The message was repeated twice, then the transmitter was silent. Too long a silence. There was no reply. Don't stop! Keep sending, Buddy. Can you? Are you injured? Tell me! The frantic call resumed "SOS SOS Knwsly Hall torpedoed. Position. . ." Then silence. Finally an answer, a painfully slow response. The fellow must be falling asleep at his key. Impatiently, Dale copied the message: "Knowsley Hall yours received. Gbrltr." Then, again, silence.
    "Is that all?" In frustration Dale talked to thin air. " 'Yours received?' Tell the poor guy help is coming. Or not coming, but tell him something, you lazy lout." His fist itched to say what he thought. So strong was the urge that he left the radio room and went on deck. There he saw the gunnery crews firing frantically at nothing. Chris whirled the stem gun from starboard to port spraying the ocean, blindly keeping six water spouts standing on the surface. He kept it up until Baxter called, "Cease fire."
    By then Ryan had rounded up all available crewmen and repeated his standing order, "Watch for a moving periscope. Looks like a white rooster tail."
    Dale returned to his post. Later Andy Wagner poked his head inside the door. "Come have a look."
    There, to the eastward, coming up in a tornado of black smoke that hugged the water, came two destroyers climbing huge bow waves.
    While they were a quarter mile away we could hear the drumming, roaring sound of their fans and engines which were beating the water into a small turbulent mountain astern. A rim of reddish and blue haze whipped and curled back from their stubby funnels. As they drew past us British tars pulled themselves along her decks by hand guideropes, their shirttails snapping and fluttering in the forty knot breeze as they rushed on.
    That's more like it, Dale thought. Heaving a sigh of relief, he returned to his post.
    The Vigo moved closer to Cape Spartel. Still in full daylight, the lighthouse beacon did its work sweeping a grey, empty surface. Seeing the lonely landmark sent an icy chill down Dale's spine. They were entering the narrow Straits.
    Ryan used the risky strategy of running the Vigo close to the coast of Africa, not wanting to leave room for a submarine to hide submerged between him and shore. They were entering the Strait at a dangerous time of day; U-boat attacks were known to occur most often at dawn and dusk. Hurry, darkness.
    Night was descending when Merrick entered the radio cabin. Dale handed him the latest radio report of enemy locations but Merrick barely looked at it. He'd come to blow off steam, "He won't let go of the helm." Dale knew he was talking about the captain.
    "What's wrong with that?"
    "He's going to run us aground. The man acts crazy. He says he'll ram any submarine he sees."
    The phone rang.
    "Strange ship approaching to port." Dale scanned the wavelengths, heard a radio signal and quickly called the bridge.
    "Just heard a Telefunken open up. The operator of that passing ship reported our position." He repeated the position to the chief mate. The bridge officer chuckled "He's wrong by five miles." So far so good.
    A corsair, an ancient lateen-rigged sailing vessel common to the region, approached dangerously close. Vigo lookouts scanning the vessel found it loaded with goats and sheep and manned by men wearing robes and turbans. Among them, however, Ryan spotted a blonde-headed observer with binoculars. Without hesitation or warning he turned the Vigo's helm hard over, cutting across the path of the oncoming boat. Capt. Ryan hollered into the speaking tube, "Pour it on down there, we're almost through," as the corsair veered away to avoid collision. John Reynolds doubled the number of men heaving coal and the Vigo's French engines pounded louder and harder, producing the best speed logged since leaving New York. From the bridge Brennan sang out, "Eight knots."
    Lookouts strained to see through the deepening darkness. They watched for colored lights to show them the channel through the narrowing waters near Tarfia, Spain, knowing that at any moment a torpedo might come streaming through the darkness. Dale's radio screamed SOS calls, and he received a warning of a submarine. The U-52 was active off Cape Spartel. At the moment he finished copying the information, an explosion rocked the Vigo.
Pages 181-182:

    He recalled the story told by a wirelessman one evening in a waterfront bar. The man was a survivor of another sunken tanker, the Moreni.
    "We weren't torpedoed. All gun fire. Guess the U-boat Commander knew being a tanker, fire would finish us. Damn near did. Burning oil everywhere. I had to swim under it." A trembling hand tried to light a cigarette. Help came from fellow wirelessmen all around the table. Wide-eyed, blinking, they waited for him to continue.
    "How did you know to quit sending?"
    "No choice," he spoke in a whisper. "A shell passed clean through the radio cabin . . . took the aerial but missed me."
    "What about your assistant?"
    "Curran, poor devil, drowned. He'd gone on deck to help pass shells. An explosion uprooted the gun. Everyone dove overboard including me." He crushed out the cigarette and took a long drink of water.
    "How were you saved?"
    "Saw a boat. Swam toward it. The ship upended, propellers still spinning. Hung there then slid down through her own debris and burning oil. Fuel meant for the Italian Army went up in smoke."
    "Then what happened?"
    "Thought sure we were next. The submarine turned toward us but didn't fire." The wirelessman told of encountering a German U-boat captain who spoke perfect English. Leaning from the conning tower, he asked survivors the name of their ship, then invited them aboard the submarine where he personally dressed their wounds, gave them dry blankets, hot coffee and biscuits. Bewildered, the men listened to their attacker explain that he used to live in Chicago until called back to Germany for war service.
    "We thought we'd been taken prisoner. But he let us go. He said help was on the way, clanged the hatch cover shut and disappeared."
Page 240:

    Captain Ryan handed out pay envelopes to his officers and crew, asking Dale to wait until last. The envelopes contained a war bonus -- extra money for hazardous duty -- and the men happily counted their money, shook hands and left. Then the captain walked with Dale to the radio cabin before giving him his envelope. Inside was $120, far less than he expected. "Where's my bonus? I'm supposed to get a hundred percent war bonus like the rest of the crew."
    Ryan shook his head, "Read the note." The message from the ship's owner said, "This man works for the Marconi Company. No bonus required."
    "Can they get away with this?" asked Dale.
    "They say it's Marconi Company policy."