The Great Sub Flub of 1940

A 1940 DIY extortion plot looked brilliant. Its execution? Not so much.

Walter Minx. Photo courtesy of Milwaukee Journal Sentinel

Walter Paul Minx was 23 years old in 1940. He was slender and fidgety, with the kind of sharp-featured handsomeness that the movies had taught people not to trust. He was a German by birth and at heart, but possessed a distinctly American set of ambitions. He admired Adolf Hitler and had once been a proud member of the Nazi Party. He also wanted to build a business, to earn himself a name and a fortune. Friends and family called him “the Macher,” a German idiom for an important man who had influence and made things happen. Its literal translation was “the doer.” It was often used ironically.

Walter Minx came to Milwaukee from Germany in 1925 with his parents, his older brother, Kurt, and a sister. Although his formal education had stopped after seventh grade, Walter displayed an intuitive mechanical brilliance from an early age. He was an inveterate builder and tinkerer. He had once built a working motorboat, and he later had constructed a small plane that, as the family legend went, he had actually been able to fly.

As Hitler began his conquest of Europe and news of naval warfare made local headlines, Walter dreamed up a scheme in which he and Kurt could secretly salvage torpedoed military ships using a homemade submarine. He designed and began to build a 20-foot sub that would have been able to travel at 25 miles per hour. He gave up on the project before it was completed, but, as always his mind kept working. He had no doubt he could build a functional treasure-hunting sub. He just needed a target closer to home.

On April 15, 1940, an item appeared on page six of The Milwaukee Journal‘s second section. It pictured Rowland H. Davie, general manager of Milwaukee’s Sears stores, surrounded by smiling employees as he passed out envelopes containing $62,000 in profit-sharing funds the company was distributing. Davie was middle-aged, bespectacled and grinning, seated behind a stately desk and beaming with the visage of an important man.

A few months earlier, Minx had installed decorative ironwork cashier’s cages in the credit department of one of Davie’s Sears stores, located on North Avenue. He had since left the firm responsible for the Sears job to start his own company. He had been getting steady work, but was having trouble with the capital funds needed to truly start seeing a profit. Seeing the photo of Davie in the newspaper, Minx thought he looked like a man with much to lose and cash to spare.

Over the next few months, Minx formulated his plot. He would contact Davie and threaten him with death and the destruction of two of his Milwaukee stores if he did not pay $100,000 in cash. To show that this was not an idle threat, Minx would detonate a small pipe bomb at the North Avenue store the day after the letter was delivered. Davie would be ordered to charter an airplane with enough fuel to fly 75 miles from the Curtiss-Wright airfield (now Timmerman Airport) and await instructions. Minx would have the plane fly east, over Lake Michigan, where he would be hidden beneath the water in a homemade submarine. A pair of lights would float above the sub, indicating where the cash should be dropped. After the drop, Minx would surface, collect the loot and re-submerge. As he made his way back towards the mainland, Minx would transfer the cash into a water-tight inner-tube. A few hundred feet off of Bradford Beach, he would scuttle the sub and swim back to a secluded part of shore, where his car would be waiting for him.

Kurt Minx, Walter’s brother. Photo courtesy of Milwaukee Journal Sentinel

To aid in the plan, Minx recruited Kurt and their 28-year-old brother-in-law, Daniel Carter. As the mastermind, Walter claimed half of the $100,000, while Kurt and Carter agreed to take $25,000 each. Throughout the summer, Walter worked on the pipe bomb in the North 11 Street shop he rented for his ironwork business, building the weapon side-by-side with his regular work. It took him several weeks to perfect the device and outfit it with a “blast” suitable for sending his message.

Building the submarine went much quicker. Using sheet metal and a battery-operated automobile motor, Minx completed the craft in about a week, working on it at his parents’ Holton Street home. The design for the 7-by-3-foot boat was entirely his own. After he had completed the craft, Walter sat inside it as his brother dumped bucket after bucket of water over it, checking for leaks. As Walter expected, it was watertight.

On July 23, the gang was ready to make contact. Kurt pulled to the curb on Shorewood Boulevard as his car neared the address Walter had found in the telephone directory. Walter got out and walked forward briskly while Kurt pulled away and rounded the corner. In Walter’s pocket was a two-page, punctuation-free note, written in crude, all-caps print relaying the details of the cold-blooded plot. It told Davie to run an ad in the next day’s paper reading “Joe Will Be At Home, R.H.D.” if he agreed to their terms. The note was signed “WE.”

The note that set off the plan. Photo courtesy of Milwaukee Journal Sentinel
The house at the wrong address

As he approached 2612 E. Shorewood Blvd., Walter cut a quick path across the grass, tossed the envelope near the porch and hastened away, quickly turning the corner and jumping into this brother’s waiting car. For all the brilliance that Walter displayed, he was prone to boneheadedness. Case in point was the delivery of the extortion letter. Rowland Davie did not live at 2612 E. Shorewood Blvd. He never had. Circuit Court Judge William Shaughnessy lived at 2612 E. Shorewood, and his daughter, sitting on the porch at the time, had witnessed Walter drop the letter. She told her mother about the odd passerby, and the mother retrieved the letter, read it and immediately phoned the police.

The next afternoon, with the police watching the North Avenue Sears, Kurt drove Walter there with the armed pipe bomb hidden in an oil can. Familiar with the store’s layout and oblivious to the additional guard on hand, Walter casually walked to the third floor and slipped through a door marked “employees only.” He stashed the can near some lawnmowers and breezed out of the building undetected. At 6:18 p.m., after the store had closed, the bomb went off, blowing a hole in a wall and damaging some merchandise. If police thought the note was a hoax, the blast eradicated that idea. What they had now was a manhunt.

Walter called off the original date for the flight when an evening thunderstorm made conditions on the lake unsuitable for navigation. Not satisfied with the bucket tests in his parent’s yard, Walter also wanted to be sure all was functional with his sub before they contacted Davie with directions for the flight. He needed to take the sub at least 10 miles offshore for the drop – a round trip of over six hours.

Just after dark on Saturday night, Walter and Kurt attached a 100-pound oxygen tank to the sub, enough for 48 hours, and drove to the foot of Henry Clay Street in Whitefish Bay, where they eased it into the water. Walter climbed inside the narrow vessel and Kurt affixed the conning tower (the structure that contains the periscope). Bolting the tower into place and switching on the battery-powered propeller, Walter started out into the lake. Safely away from the beach, he opened a faucet that connected to the sub’s outer shell, filling a pair of gallon tin cans with lake water. As the cans filled, Walter dumped them into the craft’s hollow keel for ballast. 

Shoreline at the end of Henry Clay Street in Whitefish Bay, where Minx launched his sub. Photo by Moriah Bame

Kurt watched nervously on the beach as the little sub sank slowly into the lake. As 10 p.m. passed, the sub still hadn’t fully submerged. Worse yet, a crowd of curious passersby had begun to gather on the beach. Kurt stammered something about the two being hobbyists testing their latest creation. Back in the sub, Walter had filled the keel and the cans. But still the tower stuck out from the water like a tin buoy. After Walter tried everything he could think of for another hour to fully immerse the craft, the police showed up.

Noting the group of people on the beach and the Minx party conversing in the shallow water, a pair of Whitefish Bay police officers broke up the crowd and demanded to know what the two young men were doing on the beach after hours. They repeated the half-true “hobbyists” excuse and promised to head home. They were so shaken by the run-in, they left the craft hidden at the beach and completely forgot to contact Davie. The police had been huddled with Davie at his home for days, waiting for their orders so they could send a look-alike detective to the airport and a small army of cruisers into the streets, to follow the plane via short wave radio instructions.

Having been spotted by numerous people and the police in their partially functional submarine, Walter decided that a water recovery of the cash was no longer feasible. Even more shaken by the failed test run, Daniel Carter – having played no real role in the plot – backed out and left his share of the loot to the Minxes. Over the next three days, via a series of letters (mailed to Judge Shaughnessy’s Shorewood home), the plotters instructed Davie to have a man on a motorcycle ready with the cash. He would be given a specific time and place to await further instructions. Davie’s life was again threatened and “WE” said they were not afraid to die.

While the Minxes scrambled to save their crumbling plot, detectives were narrowing the list of suspects. After consulting local hardware shops on the fragments left by the pipe bomb, police determined that the bomber was likely someone involved in decorative ironwork. In particular, they focused on a firm that had been commissioned by the Sears store earlier that year to install cashier’s cages. Checking on that firm’s employees, they took a significant interest in one man no longer with the company – Walter Minx.

On a visit to Minx’s shop, detectives learned that the tire store that had been leasing Minx his space had recently evicted him. Searching the vacant workshop, police removed nearly 500 pounds of materials that the hard-luck ironworker had left behind, including several pieces identical to those used in the bomb.

Meanwhile, Walter crafted a series of instructions for Davie’s motorcycle rider. On Thursday, August 1, a plainclothes police officer mounted a beat-up bike at North 36th Street and West North Avenue. At 8 p.m., a pair of children, paid 30 cents by Walter, approached the man with a hand-drawn map. As the officer started off, two unmarked police cars followed behind. The map took him all over the Northwest Side, landing him at a corner where he was instructed to look for a fire hydrant. Tucked near the hydrant was another map with another convoluted route.

The end target was a vacant lot with a large “For Sale” sign. The motorcyclist was to leave the cash beneath this sign. After the officer left the package – which was filled with blank sheets of paper – officers hid at the site, waiting to nab their man.

But Walter Minx had already lost interest in the cash. To him, the thrill of it all was in the doing, not the payout. He later admitted that, by the time he had arranged for the wild bike ride, he didn’t even want the money anymore. He considered writing Davie again and being straight about his financial troubles and offering to forget the whole thing for $1,000. He considered writing him and calling the whole thing off. Minx circled the drop spot several times, unaware of the police presence, but could not bring himself to take the money. The project was busted and he was just as content to let it sit, half-finished, just as he had done with his plan to loot naval wrecks and a dozen other projects he had dreamed up. So Minx went home with no next move in mind. He was arrested the next morning.

In a strange way, it was his arrest that brought Minx the validation he’d sought from his plot. With newspapers, both local and national, marveling at his weird mechanical genius, Walter was a gracious suspect. He confessed almost immediately after being shown the scraps from his shop, and spared no detail of his plan to reporters. He even assisted a Milwaukee Journal sketch artist in making a drawing of his “U-boat,” pointing out the valves he had missed and giving the function of each. Facing up to 17 years in prison, and with his brother and Carter facing similar penalties, Walter stood beside his submarine, beaming like a proud parent. “Send over a copy of the paper with this write-up in, will you?” he asked the reporters.

Walter Minx’s brother-in-law, Daniel Carter. Photo courtesy of Milwaukee Journal Sentinel

Three weeks later, Walter pleaded guilty to attempted extortion and malicious destruction of property. Kurt pleaded not guilty, despite having confessed the night he was arrested. Walter tried to take the full blame, testifying – contrary to his initial confession – that Kurt was an unwitting participant and had committed no crime. Despite Walter’s efforts, both were convicted. Walter got 14 years, and Kurt got 12. Each would be eligible for parole in a year. Charges against Carter were dismissed.

Walter Minx ended up serving six years of his sentence. He made news several times during his term – for applying for a pardon, for disavowing his Nazi past and seeking work in a munitions plant, and for walking away from a work camp in an ill-advised escape attempt.

After his release, Minx lived a quiet, industrious life. He built a business, raised his kids and spent his free hours building a 36-foot cabin cruiser in his backyard. In a 1993 interview with The Milwaukee Journal, his last before his death in 2009, Minx said he was proud of the life he had led, but found it difficult to live down the misguided ambition that brought him into the spotlight. “I am bitter for 50 years,” he told The Journal, I paid my debit to society. I was guilty, there was no question about it, [but] all my work is for naught. I’m still an ex-con.” ◆

Tune in to WUWM’s (FM 89.7) “Lake Effect” June 28 at 10 a.m. to hear more about the story.

Matthew J. Prigge has written many articles on history for the magazine.

‘The Great Sub Flub’ appears in the June 2017 (City Guide) issue of Milwaukee Magazine.

Find it on newsstands beginning May 29, or buy a copy at

Be the first to get every new issue. Subscribe.