How a sand sci­en­tist helped win World War II

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THE AF­TER­NOON OF JAN­UARY 11, 1941, WAS SLEEPY AND QUIET AT THE FORT DEEP IN THE SA­HARA IN ITAL­IAN-OC­CU­PIED LIBYA, IN AN OA­SIS CALLED MURZUQ. THOUGH THEIR COM­RADES BACK HOME WERE EM­BROILED IN THE SEC­OND WORLD WAR RAG­ING ACROSS EUROPE, THE ITAL­IAN SOLDIERS GUARD­ING THIS OUT­POST, A STRATE­GIC ROAD JUNC­TION, FELT COM­FORT­ABLY DIS­TANT FROM THE BAT­TLE. AS FAR AS THEY KNEW, THE CLOS­EST EN­EMY WAS HUN­DREDS OF MILES AWAY, IN BRITISH-CON­TROLLED EGYPT. MURZUQ’S DE­FEND­ERS WERE SO RE­LAXED, SOME OF THEM WERE OUT­SIDE THE WALLS FOR AN AF­TER-LUNCH STROLL. Out of nowhere, a col­umn of mil­i­tary trucks and jeeps came roar­ing to­ward the fort, spit­ting ma­chine-gun fire. The invaders—British, French, and New Zealan­der troops—split into two groups. One ham­mered the com­pound with mor­tars and ma­chine-gun fire, while the sec­ond raced to­ward a nearby air­field. Be­fore most of the aero­drome de­fend­ers had time to reach their weapons, the com­man­dos over­ran them. The Al­lied troops leaped from their ve­hi­cles, dashed into the hangar, poured ga­so­line over the three bombers in­side, and set them ablaze. Snatch­ing up sev­eral Ital­ians as pris­on­ers, the strike force sped away, dis­ap­pear­ing into the Sa­hara.

You can’t blame the Ital­ians for hav­ing let down their guard. The at­tack seemed im­pos­si­ble. How could nearly two dozen en­emy ve­hi­cles have trav­eled, un­de­tected, across all those miles of rock and sand?

That night, from a re­mote desert camp, the Al­lied soldiers—mem­bers of an elite squad known as the Long Range Desert Group—re­lated news of the as­sault via a wire­less trans­ceiver to British head­quar­ters in Cairo, Egypt. There, Ralph Al­ger Bag­nold, a tall, sinewy British army lieu­tenant colonel, re­ceived the re­port with sat­is­fac­tion.

Bag­nold had founded the Long Range Desert Group the pre­vi­ous year, and had hand­picked and trained its soldiers. It was his un­matched skills as an ex­plorer of the Sa­hara that had made it pos­si­ble for the com­man­dos to travel through the track­less waste­land for the 16 days it had taken to reach Murzuq. Bag­nold, a rare com­bi­na­tion of sol­dier and sci­en­tist, un­der­stood the desert bet­ter than any Euro­pean alive. He had not only de­vised the tech­niques and in­no­va­tions that al­lowed cars to drive atop oceans of sand, but he had also un­rav­eled the mys­tery of how the grains of sand them­selves move. His ca­reer al­ready in­cluded ac­tion in two dif­fer­ent world wars. He couldn’t have known at the time, but one day it would range across two dif­fer­ent worlds.

BAG­NOLD WAS BORN IN 1896, IN DEVONPORT, ENG­LAND,

to a gen­teel fam­ily with a long tra­di­tion of mil­i­tary ser­vice. His fa­ther had fought in some of Great Bri­tain’s colo­nial bat­tles in Africa but served mainly as an en­gi­neer. Con­ver­sant with car­pen­try, met­al­work­ing, and other trades, he was known for be­ing able to make, fix, or jury-rig just about any­thing, skills he passed on to his son. Young Ralph started study­ing en­gi­neer­ing at age 13. Scorn­ing foot­ball and cricket, he spent his af­ter­noons learn­ing to use lathes, met­al­work­ing tools, and milling ma­chines.

By the time he was 19, in 1915, Bag­nold was a sec­ond lieu­tenant in the British army and en­rolled in its ven­er­a­ble mil­i­tary en­gi­neer­ing school. “We learned a great deal that was last­ingly use­ful—how to dig al­most ef­fort­lessly, how to lift and move great weights with rope and pul­leys, a bit of sur­vey­ing and map­mak­ing, and how to de­stroy with ex­plo­sives,” Bag­nold wrote in Sand, Wind and War, his 1990 au­to­bi­og­ra­phy. “Still more im­por­tant, we learned to im­pro­vise.”

He also learned to de­sign bat­tle trenches, and soon found him­self fight­ing in them. Sent to France in World War I, Bag­nold served on the front lines of some of its most bru­tal bat­tles. “There was al­ways some poi­son gas around from Ger­man shells,” he re­called with trade­mark British re­serve. “Some­times we had to don our clumsy masks, but usu­ally we just coughed our way through.”

In the mid-1920s, the army posted Bag­nold to Egypt. The desert en­tranced him—its im­men­sity, its mys­tery, the al­lur­ing fact that so much of it was un­known. “In Cairo we had at our very doorstep the edge of a vast field for real ex­plo­ration,” he wrote in his mem­oir. The east­ern Sa­hara is “the most arid re­gion on Earth, wa­ter­less and life­less save for a few arte­sian oases scat­tered sev­eral hun­dred miles apart.”

Bag­nold’s peers told him the sands couldn’t be crossed in a motor ve­hi­cle. “This struck me as an ir­re­sistible chal­lenge,” he re­called. Peace-time sol­dier­ing al­lowed him plenty of time to ex­plore. With friends, he started ven­tur­ing into the waste­lands with the stur­di­est ma­chines he could find, Model T and Model A Fords. The group ranged around east­ern Egypt, the Si­nai, what was then Tran­sjor­dan and Pales­tine, and fi­nally into the Sa­hara it­self, pen­e­trat­ing deeper than any Euro­pean had ever gone.

Ford had not de­signed its cars for this kind of off-road­ing. So Bag­nold, with plenty of trial and er­ror, de­vised a se­ries of mod­i­fi­ca­tions that al­lowed his crew to drive in sand, and to sur­vive for weeks at a time in the parched ter­rain. To con­serve wa­ter for the cars, Bag­nold sol­dered pipes onto the ra­di­a­tors to cap­ture es­cap­ing steam, which col­lected into a metal can, con­densed, and re­cir­cu­lated. Be­cause the mag­netism of the ve­hi­cles’ ample metal and mov­ing parts threw off con­ven­tional compasses, Bag­nold nav­i­gated by bolt­ing a sun com­pass

onto the dash­board. To cut down weight, he stripped off bumpers, hoods, and wind­shields, and even re­placed por­tions of the car bod­ies with wood. Know­ing the un­holy beat­ing the el­e­ments would in­flict on the ve­hi­cles, the ex­plor­ers didn’t just pack spare tires; they prac­ti­cally packed spare cars. Ev­ery few days they spent hours patch­ing rub­ber by hand, or swap­ping out dam­aged epicyclic gears and sus­pen­sion springs.

Dur­ing these years of ex­per­i­men­ta­tion, Bag­nold drove some 20,000 miles, much of it in track­less ter­ri­tory. Of course, the cars also got stuck. To cope, Bag­nold used per­fo­rated steel “chan­nels”—es­sen­tially, por­ta­ble ramps—and can­vas-and-rope mats to lay un­der the wheels to gain trac­tion. They worked but with tremen­dous ef­fort: “At one mo­ment you would be do­ing a steady thirty miles an hour to the re­as­sur­ing whine of the tyres; the next halted dead in five yards with the car up to its axle in a dry ‘quick­sand,’” wrote one of his trav­el­ing com­pan­ions, Wil­liam Boyd Kennedy Shaw, in his mem­oir Long Range Desert Group: Be­hind En­emy Lines in

North Africa. “Us­ing sand chan­nels and sand mats, and with a dozen sweat­ing and curs­ing men, the truck would be ex­tri­cated two yards at a time.” ad­ven­ture, but Bag­nold be­came fas­ci­nated by the ti­tanic dunes and the tiny grains that formed them. In the desert, he later wrote, “in­stead of find­ing chaos and dis­or­der, the ob­server never fails to be amazed at a sim­plic­ity of form, an ex­ac­ti­tude of rep­e­ti­tion and a geo­met­ric or­der un­known in na­ture on a scale larger than that of crys­talline struc­ture. In places vast ac­cu­mu­la­tions of sand weigh­ing mil­lions of tons move in­ex­orably, in reg­u­lar for­ma­tion, over the sur­face of the coun­try, grow­ing, re­tain­ing their shape, even breed­ing.”

How, he won­dered, did the dunes keep their shape while trav­el­ing? Why did sand ac­cu­mu­late on them in­stead of spread­ing out? How did the in­di­vid­ual gran­ules move? Ge­ol­o­gists had stud­ied the ori­gins of sand, and en­gi­neers used em­pir­i­cal tech­niques to pre­dict sed­i­ment flows, but no one had ap­plied the prin­ci­ples of physics to ex­plain the move­ment of the grains.

Af­ter re­tir­ing from the army and re­turn­ing home, Bag­nold set out to be the first. Ever the im­pro­viser, he built a wind tun­nel out of ply­wood and glass and set it up in bor­rowed space at Imperial Col­lege Lon­don. “I felt it was re­ally just ex­plor­ing in an­other form,” he later rem­i­nisced. Us­ing his prac­ti­cal knowl­edge of physics, math­e­mat­ics, and en­gi­neer­ing, he ran hun­dreds of sand sam­ples through the tun­nel. He recorded and pho­tographed the ways in which wind at vary­ing strengths moved dif­fer­ent-size grains, and how the grains in­ter­acted on the ground and in the air.

He found that as winds lift sand into the air, the grains af­fect the wind’s move­ment. And as the wind’s move­ment of sand changes the shape of the desert floor, that shift­ing sur­face af­fects how both move. Among Bag­nold’s key dis­cov­er­ies was that wind­blown grains jump, a move­ment known as sal­ta­tion: They briefly rise into the air, crash back to the ground, and bounce up again. In the process, they can trans­fer en­ergy to larger grains on the ground, nudg­ing them for­ward in a process called sur­face creep.

To de­scribe these move­ments, Bag­nold de­vel­oped math­e­mat­i­cal for­mu­las that he later checked against real-world con­di­tions in the Egyp­tian-Libyan desert dur­ing a re­turn trip there in 1938. At one HE AND HIS FRIENDS MIGHT HAVE BEEN IN IT FOR THE

point, he lost his gog­gles. “I spent some very un­com­fort­able hours sit­ting in the open, di­rectly ex­posed to a vi­o­lent sand­blast, try­ing to keep my eyes open while tak­ing read­ings from an ar­ray of gauges and sand traps,” he re­called in his mem­oir. “The pur­pose of eye­lashes was very ev­i­dent.”

Af­ter five years of re­search, he had enough data to write a book, The Physics of Blown Sand and Desert Dunes. It was the first sci­en­tific in­ves­ti­ga­tion of the sub­ject, and is con­sid­ered a foun­da­tional text in the study of ae­o­lian, or wind-driven, pro­cesses. “His book was sem­i­nal,” says Haim Tsoar, a lead­ing ex­pert in the sub­ject at Is­rael’s Ben Gu­rion Univer­sity of the Negev. “I think he was a ge­nius.”

BUT BE­FORE THE BOOK COULD BE PUB­LISHED, WORLD WAR II BROKE

out. Sum­moned back to the army, Bag­nold found him­self once again in Egypt. There, Bri­tain’s troops faced off across the Sa­hara against a larger Ital­ian fas­cist force in Libya. Ex­am­in­ing maps of the re­gion, Bag­nold re­al­ized that his ec­cen­tric hobby could be con­verted into a prac­ti­cal weapon.

In 1940, with Italy plainly pre­par­ing to in­vade Egypt from Libya, Bag­nold pitched the British com­man­der, Gen. Archibald Wavell, on his idea: a spe­cially trained, fast-mov­ing com­mando force that could strike from deep in the desert. Wavell was sold. He gave Bag­nold a free hand to sow what­ever havoc he could in Libya. Bag­nold re­cruited vol­un­teers, ran­sacked mil­i­tary ware­houses, and rum­maged Cairo junk shops for his un­con­ven­tional needs: san­dals, Arab head­dresses, trouser clips to hold down wind-tossed maps, and lots of spare tires.

Bag­nold took a small fleet of Chevro­let 1.5-ton trucks and out­fit­ted them with his sand chan­nels, sun compasses, and other in­no­va­tions. He cut off wind­shields, in­stalled ex­tra-strength springs, and mounted Bo­fors anti-air­craft guns on their beds. He or­ga­nized teams into 30-man units. “These pa­trols had to be com­pletely self-con­tained for long in­de­pen­dent ac­tion, out of reach of any pos­si­bil­ity of help,” Bag­nold told a ra­dio jour­nal­ist in 1941. “Each needed to be an army in minia­ture.”

A typ­i­cal pa­trol com­prised around 10 trucks and jeeps. One truck car­ried com­mu­ni­ca­tions and nav­i­ga­tion gear. An­other toted heavy weapons. The rest carted

fuel and sup­plies. The LRDG’s raids be­came leg­endary; even to­day the group has many fans, fore­most among them Jack Valenti, founder of the Cal­i­for­nia-based Long Range Desert Group Preser­va­tion So­ci­ety. Valenti and his com­rades have spent num­ber­less hours and tens of thou­sands of dol­lars re­search­ing and re-cre­at­ing the LRDG’s trucks and jeeps. He and a few friends showed off one of them at a con­ven­tion of mil­i­tary-ve­hi­cle en­thu­si­asts in North­ern Cal­i­for­nia this past April. The roof­less 1.5-ton Chevy truck, built in the early 1940s, was fit­ted out with rolled-up can­vas sand mats clamped to the front bumpers, and per­fo­rated steel sand chan­nels—the ramps to put un­der stuck wheels—lashed along the sides. A sun com­pass was bolted to the wooden dash­board. The uncovered cargo bed was neatly packed with spare parts, med­i­cal gear, wooden crates for am­mu­ni­tion, and can­vas bags of ra­tions, in­clud­ing cans of Libby’s corned beef, an ac­tual brand Bag­nold’s men ate. “Bag­nold was a bril­liant man,” says Kevin Can­ham, a snowy-bearded for­mer high school teacher, Navy vet, and preser­va­tion so­ci­ety mem­ber. “He was the World War II ver­sion of Lawrence of Ara­bia.”

In fall 1940, Bag­nold’s LRDG, made up of a few old com­rades plus 150 New Zealand vol­un­teers, rode into ac­tion. Cam­ou­flaged amid the dunes, they spied on en­emy troop move­ments, ra­dio­ing their in­tel­li­gence back to British forces in Cairo. They launched light­ning sur­prise raids on Axis gar­risons and air­fields, then van­ished back into the ex­panse of the Sa­hara. They cul­ti­vated a desert-pi­rate look, sport­ing Arab head­dresses, un­kempt beards, and a scor­pion in­signia, to the ex­cite­ment of the press back home.

Their im­pact be­lied their size. One year af­ter the LRDG took to the field, Wavell wrote in a dis­patch: “Not only have the pa­trols brought back much in­for­ma­tion, but they have at­tacked en­emy forts, cap­tured per­son­nel [and] trans­port and grounded air­craft as far as 800 miles in­side hos­tile ter­ri­tory. They have pro­tected Egypt and the Su­dan from any pos­si­bil­ity of raids, and have caused the en­emy…to tie up con­sid­er­able forces in the de­fense of dis­tant out­posts.”

In July 1941, at age 45, fi­nally weary of the heat and harsh liv­ing con­di­tions, Bag­nold handed over the LRDG com­mand and took a post in Cairo. The group fought on un­til the Axis was de­feated in Africa in 1943. It went on to mis­sions in Greece, Italy, and the Balkans be­fore dis­band­ing at the war’s end.

WITH PEACE, BAG­NOLD RE­TURNED TO ENG­LAND, MAR­RIED,

had two chil­dren, and set­tled down in ru­ral Kent. His ca­reer as a desert fighter was over, but he was about to launch a new vo­ca­tion as a desert ex­pert. His work on the physics of wind­blown sand had, to his as­ton­ish­ment, got­ten him elected a Fel­low of the Royal So­ci­ety— one of Bri­tain’s pre­mier sci­en­tific hon­ors. “It was more sur­pris­ing be­cause I was merely an ama­teur sci­en­tist with no aca­demic stand­ing,” he wrote in his mem­oir. There was an up­side to that: “Be­ing an ama­teur, a free lance who never held any aca­demic post or had any pro­fes­sional sta­tus, I had the rather un­usual ad­van­tage of con­sid­er­ing prob­lems with an open mind, un­bi­ased by tra­di­tional text­book ideas that had re­mained untested against facts.”

Bag­nold’s knowl­edge proved valu­able. Oil and gas com­pa­nies build­ing in­stal­la­tions in the desert sought him out for help un­der­stand­ing how to cope with the ever-shift­ing sands. He ad­vised British Pe­tro­leum on build­ing a pipe­line across a huge swath of desert in

Libya, and ex­plained to oil ex­ec­u­tives in Iran the ba­sics of how sand moves and how to build fences to keep it out.

But Bag­nold de­voted most of his en­ergy to re­search, turn­ing his at­ten­tion to the study of how rivers trans­port sed­i­ments, a field in which he also made im­por­tant con­tri­bu­tions. His 50-years-long cre­ative and in­ter­dis­ci­pli­nary ap­proach to sed­i­ment physics “en­abled to­day’s earth sci­en­tists and en­gi­neers to plan and pur­sue projects equipped with a deep, if still im­per­fect, un­der­stand­ing of these crit­i­cal nat­u­ral pro­cesses,” wrote the late ge­ol­o­gist and fel­low arenophile Michael Wel­land. Bag­nold au­thored nearly 50 sci­en­tific pa­pers and racked up pres­ti­gious awards from the Na­tional Acad­emy of Sciences and the Ge­o­log­i­cal So­ci­ety of Amer­ica, as well as two hon­orary doc­toral de­grees. Still, “he was ex­tremely mod­est,” says his son, Stephen Bag­nold. “Nine-tenths of him was al­ways hid­den.”

Bag­nold’s ca­reer could have ended with World War II, and he would still be as­sured a place in the his­tory books. But there was one more phase to come. In the 1970s, NASA called. It wanted him to ap­ply his knowl­edge of earth sci­ence to an­other planet. The agency’s first Mars or­biter had spot­ted what ap­peared to be not only sand, but dunes. It wanted Bag­nold to help it un­der­stand these for­ma­tions. On Mars, says Bethany Ehlmann, a re­search sci­en­tist at NASA’s Jet Propul­sion Lab­o­ra­tory, “there are the same physics but with to­tally dif­fer­ent con­stants of grav­ity, grain den­sity, and at­mo­spheric pres­sure.”

For sev­eral years, Bag­nold worked with the agency, in­clud­ing coau­thor­ing a pa­per with Carl Sa­gan. “I spent one evening at a Mc­Don­ald’s with a small group of young sci­en­tists from NASA’s Jet Propul­sion Lab­o­ra­tory in Pasadena,” Bag­nold wrote later in his au­to­bi­og­ra­phy. “It was fas­ci­nat­ing for an old man of eighty-one to lis­ten to their ca­sual talk of nav­i­gat­ing a space­craft two hun­dred mil­lion miles away as eas­ily as an aero­plane. Man had not be­gun to fly at all when I was born.”

Al­most un­til the end of his life, the old sol­dier-sci­en­tist stayed ac­tive, pub­lish­ing his fi­nal pa­pers—one, oddly, in­cludes an anal­y­sis of the ran­dom dis­tri­bu­tions of word lengths in dif­fer­ent lan­guages— in the 1980s. His last pa­per ap­peared in 1986, when Bag­nold was 90 years old. He died four years later.

“He’s still very much present in the modern field,” Ehlmann says. She should know. Over four months, be­gin­ning in late 2015, Ehlmann helped lead NASA’s Cu­rios­ity rover on the first ex­plo­ration of a dune field con­ducted on an­other planet. The rover uncovered im­por­tant in­for­ma­tion on the his­tory of the Mar­tian land­scape and the chem­istry of its com­po­nents. In honor of the man who “rev­o­lu­tion­ized our un­der­stand­ing of ae­o­lian pro­cesses on Earth,” as Ehlmann put it in a re­cent pa­per on the mis­sion, her team be­stowed a fit­ting name on the for­ma­tions. Mil­lions of miles from the near­est hu­man habi­ta­tion, the re­motest desert ever ex­plored by a man-made ve­hi­cle now in­cludes an area known as the Bag­nold Dunes.

Dune Bud­dies Bag­nold’s Long Range Desert Group tra­versed the desert to at­tack en­emy out­posts.

Desert Ace Bag­nold’s 1930s Sa­hara ex­pe­di­tions in­spired his World War II strike force.

Sol­dier and Sci­en­tist LRDG mem­bers (above), back from a suc­cess­ful op­er­a­tion; Bag­nold mea­sures wind in a sand­storm in 1938.

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