Lethal Tides: Mary Sears and the Marine Scientists Who Helped Win World War II by Catherine Musemeche was published in August, 2022, by William Morrow. It is 320 pages long with twelve pages of black-and-white illustrations. Musemeche is a pediatric surgeon, professor of surgery, and author of two previous books addressing medical topics. Musemeche dedicates Lethal Tides to her father, Frank M. Musemeche, QM3 United States Navy. Musemeche’s father was 17 when he served in the waters around Okinawa “when kamikazes started raining down from the skies … five thousand sailors were killed that day by suicide bombers.”
Lethal Tides, contrary to its title, is not a single-strand biography of oceanographer, zoology PhD, university professor, and Naval Commander Mary Sears. Rather, Lethal Tides provides biographical sketches on several scientists who contributed to naval victories for the US and the Allies during World War II. The book then goes on to describe naval battles in the Pacific Theater that relied on the support of scientists and researchers working for the military. Sears and several of her colleagues and support staff were women. Musemeche reports on the restrictions women faced in their careers. In spite of these restrictions, Sears and others served their country significantly in wartime.
Musemeche’s writing style is brisk and dense with data. It’s clear that exhaustive research went into this book, and this reader felt confident that Musemeche mastered a massive amount of material. Readers will learn of the parasites affecting barnacles, analog computers designed to predict tides, and the death tolls incurred in America’s “island hopping” approach to defeating Imperial Japan. Reports of the absurd sexism that initially thwarted Mary Sears’ career in oceanography are exasperating; similarly, one’s heart breaks for the black Marines who faced prejudice. On the other hand, one must acknowledge how expeditiously America lived up to its founding ideals. Women and black Marines made rapid progress. Battle accounts did cause this reader to tear up. Even so, Musemeche’s authorial voice is always cool. Musemeche’s objective approach is never as obvious as when she points out the facts on the ground that made the dropping of atomic bombs on Hiroshima and Nagasaki all but inevitable and certainly morally justifiable.
“The ocean would serve neither side in the war. It would merely treat more kindly those who knew it best,” wrote Columbus O’Donnell Iselin, the director of the Woods Hole Oceanographic Institution during World War II. This quote is amply supported by Musemeche’s text. Without the research conducted, and military intelligence generated by scholars like Mary Sears, it’s not at all clear that America’s defeat of Imperial Japan would have happened as it did.
Lethal Tides opens on Mary Sears studying plankton off the coast of Peru in 1941. Sears worked for the Woods Hole Oceanographic Institution, but because she was a woman, she was not allowed to board its research vessel, the Atlantis. As late as 1963, Musemeche writes, the Scripps Institution of Oceanography had not allowed women on research vessels. The State Department invited Russia to send research scientists to work on a Scripps vessel. The Russians sent Elena Lubinova. Scripps did not want to spark an international incident, and the ban on women scientists was lifted. This ban is hard to understand given that women, of course, had been traveling on passenger vessels for millennia.
Sears had to travel to Peru in order to be able to perform research from a boat. Her plankton research was designed to inform Peru’s highly lucrative guano industry. Seabirds like the Guanay cormorant and the Peruvian booby produce the guano that is harvested and sold as fertilizer. These seabirds feed on anchovies, which, in turn feed on plankton. As part of her research, Sears performed autopsies on 3,500 fish.
Sears’ great grandfather Edmund Hamilton Sears was a Massachusetts poet, preacher, abolitionist, and Harvard grad. He wrote “It Came Upon a Midnight Clear,” a popular Christmas carol. Sears’ great uncle, Alfred Wayland Cutting, was a nature photographer. When she was only six, Mary lost her mother to polio and her father to parental neglect. Sears’ male relatives had attended Harvard; she attended Radcliffe, an all-girls school known as “the annex” to all-male Harvard. Radcliffe girls were stereotyped as “unattractive with big brains … bookish, socially awkward … with stringy hair and thick glasses.”
Oceanographer and marine biologist Henry Bryant Bigelow took on Sears as his research assistant. Working with Bigelow provided Sears with a matchless education. Sears’ support allowed Bigelow to write a prospectus outlining the importance of oceanography. “M.S. fill in here,” Bigelow would write, when he wanted Mary Sears to provide for him the words he lacked himself. Bigelow’s appeal prompted the Rockefeller Foundation to fund Woods Hole. Sears resigned herself to a solitary life. “You could have a career or you could have a family but you couldn’t have both.” Even so, Bigelow would not allow Sears to make the career-necessary research trip on The Atlantis.
In 1940, Columbus O’Donnell Iselin succeeded Bigelow as WHOI director. Mary Sears was more qualified to serve as WHOI director, Musemeche writes, but she was female, and so not considered. Not just women scientists, but scientists in general, might be dismissed as contributors to the military. “Before the war, university scientists were performing cutting-edge research with potential military applications but a tribal mentality among the military brass blocked their participation in relevant projects, to the detriment of both sides,” Musemeche reports. In 1936, Iselin managed to overcome this tribal mentality. First-generation sonar was “notoriously unreliable.” A destroyer might miss a submarine idling right underneath it. Why? Iselin discovered that “the way sound traveled through water layers of different temperatures bent and distorted the sonar beam.” Ocean water would always be different temperatures at different layers, and also at different times of the day.
Mindful of this experience, Iselin offered WHOI’s services to the National Defense Research Committee. The NDRC responded positively. Mary Sears went to work on the bottom-fouling project. Marine organisms like barnacles and also plant life attach to ships and slow their speed. The goal was to discover a way for ships to remain unencumbered by marine life. Sears wanted to do more. She applied for the WAVES. She was rejected because a previous streptococcal infection in her wisdom teeth had caused arthritis. Later, Lt. Roger Revelle, assigned to the Washington, DC, Hydrographic Office, approached Iselin and asked for oceanographers. Revelle actually wanted an oceanographer to replace himself. Revelle didn’t want to be at the Hydrographic Office. Iselin did not want to let any of his oceanographers go. Finally he gestured to Mary Sears. “You can have her,” he said. Sears was, after all, just a woman, and therefore expendable to WHOI, Iselin thought. Revelle agreed. He could pull the strings to get this female reject accepted into the Navy. “I was palmed off on him,” Sears would later say. It’s a classic folktale motif. The unwanted child is the one who later saves the family from the monster.
The U.S. Navy Hydrographic Office was founded in 1830. It “published nautical charts that mapped the seas and issued sailing directions to ensure the safe navigation of the oceans.” Previously, it could rely on charts published by other countries, but wartime dried up these sources. Also, Americans were now battling in waters they’d previously never navigated. In 1942, Admiral George S. Bryan reported, “the monthly average of one million copies equals twice the yearly average of production of a few years ago.” The annual workload, Musemeche writes, increased from “500,000 to 12,000,000 in chart copies alone.”
At first, Hydro tried to maintain the tradition of hiring only men. Wartime made that impossible. Then Hydro tried to re-hire men who had previously been fired for malfeasance. No luck. Hydro then turned to old men and handicapped men. They still could not meet their staffing needs. “If the Navy could possibly have used dogs or ducks or monkeys, certain of the older admirals would probably have greatly preferred them” over women, an observer wrote. On July 30, 1942, Congress passed a bill accepting women to serve, in a tightly limited capacity, in the Naval Reserve. “Eventually, women integrated into most sections of the Hydrographic Office, undergoing intensive training in the full spectrum of chart construction tasks.”
Admiral Bryan envisioned Mary Sears digesting oceanographic information and translating it into layman-friendly form for his commanders at sea. One such item in need of translation was the bathythermograph, a complex device invented to record water temperature at varying depths, thus aiding in accurate use of sonar.
One of the many rewarding features of Lethal Tides is the glimpse it gives into life before easily accessible computers and internet searches. If I suddenly had a whim to learn today’s tide table for the remote Pitcairn Island, an internet search immediately provides me with that data. The US Navy, in World War II, had a tougher job of it. To succeed in the Pacific Theater, the US Navy required information on measurements of landing approaches, the character of bottom sediment, possible locations of underwater enemy defenses, currents, sea and swell, surf, water temperature, and salinity. The need for this information was immediate. As FDR put it, “the broad oceans which have been heralded in the past as our protection from attack have become endless battlefields.”
As the Navy outlined its needs to Sears, she “recognized that some of the data could be tracked down in scientific journals housed in libraries … data for more remote locales, such as local tides, currents, or beach conditions, had never before been compiled and did not exist in any published form, especially in the Pacific, where the US had never been to war.” Sears recognized that the Navy needed a warrior with a unique super power. The Navy needed a tireless, multilingual, experienced, innovative, librarian. Librarians are trained in tracking down information from a variety of sources, and organizing that information in a form that makes it easy to access.
Captain Eddie Rickenbacker was a World War I fighter pilot and Medal of Honor winner. In October, 1942, Rickenbacker was on a special wartime mission in the Pacific. During a flight, thanks to faulty equipment, the plane in which Rickenbacker was a passenger flew off course and had to water land for lack of fuel. Rickenbacker and others drifted for twenty-four days. Rickenbacker was a celebrity and his presumed death, and then rescue, received wide attention. This event prompted many questions. One such pressing question, given that the Navy knew that the plane had crashed, and the Navy also knew the rough whereabouts of the crash landing, “Why had it taken so long for the survivors to be rescued?” [emphasis in the original]. The Navy wanted the answer to save future sailors’ lives. Navy men were dying because they were not found in time. Oceanography, Musemeche writes, would help save the day.
Applying knowledge about drift, that is the concept of how wind and currents propel an object through water, would help save lives. Calculations involved the size and shape of the object, and how much of the object was above the surface or submerged. Sears was commissioned to, single-handedly, acquire and organize all published and unpublished research on drift. Sears then organized this massive amount of data on cross-referenced index cards. Eventually her collection of 250,000 index cards was published in the form of fifteen oversize volumes. Just one month into her tenure at Hydro, Sears produced The Drift of Objects under the Combined Action of Wind and Current. As a result, “her colleagues realized that Sears could be depended on to provide the answers the military needed to wage war in the oceans.”
In June, 1943, Harvard’s Fenner Chace, Jr. transferred to Hydro. Chace would later be named “one of the most influential carcinologists of the 20th century.” Carcinologists study crustaceans. The son of a physician, when he was six years old, Chase began collecting insects and worms and putting them on display, thus founding his own “museum.” He would eventually work in the Museum of Comparative Zoology, one of the largest and oldest such museums. Chace was agoraphobic and acrophobic. As a man, he was able to board oceanographic expedition vessels, but he didn’t want to. Chase happily spent his days alone, taxiderming, drawing, organizing, and cataloguing specimens of crab, shrimp, and lobster species.
How could the military make use of the unique and obscure skill set of a man like Fenner Chace? The military harnessed Chase’s ability to work alone on highly detailed illustrations that required complex knowledge of the ocean. Chase’s job was to create “silk handkerchiefs” for pilots. These cloth survival charts informed pilots on drift and the location of non-combatant islands. Various materials were exposed to light in a “Fade-Ometer” and submerged in salt water. Eventually rayon was chosen as the best fabric for these survival tools. Run-proof and fade-proof inks were developed, and special printing techniques, too, so that both sides of fine material could contain images. “According to the Air Sea Rescue Bulletin, hundreds of survivors praised the cloth maps and credited ‘intelligent use ‘ of them with their safe return.”
In addition to Chase, Musemeche makes brief mention of other former civilians who joined the military and put their unique skills to use. For example, “Ensign Georgia Greer traded in creating fashion displays for Bullocks department store in Los Angeles for constructing nautical charts that took men to sea. Carolyn Chadwick of Newburyport, Massachusetts, a silverware designer turned camouflage painter for the U.S. Army’s aircraft, was now using her artistic skills to make maps.”
Dora Priaulx Henry had been mentored, at UC Berkeley, by zoologist Charles Atwood Kofoid. Kofoid supported women in the sciences. Kofoid was an World War I veteran who studied parasites to help the military deal with infected soldiers. Henry, like her mentor Kofoid, became an expert in parasitology. She would move on to barnacles, eventually becoming “The barnacle lady.” She put her skills to unusual use when she was asked to determine the time of death of a corpse dragged from water. Barnacles had attached to the corpse; their growth rates would provide clues. Henry, in spite of her male mentor, suffered from sexism. She was paid less than men who worked comparable jobs and comparable hours. Henry volunteered to help the Navy with the bottom-fouling problem; she was dismissed. Undeterred, Henry was determined to turn her skills to helping America win the war.
Mary Grier was America’s top oceanographic librarian. She compiled Oceanography of the North Pacific Ocean, Bering Sea, and Bering Strait: A Contribution toward a Bibliography, published in 1941. This work listed 2,900 references, organized by topic. Compiling this work didn’t just render her an expert on the topic. It enmeshed her in a network of colleagues, researchers she could contact in the future when a new question arose.
Dora Henry and Mary Grier joined the team at Hydro.
In April, 1943, the Joint Chiefs called for JANIS reports. JANIS stood for “Joint Army Navy Intelligence Studies.” JANIS reports would “make available one publication containing all the necessary detailed information upon which may be based a war plan for military or naval operations in a given area.” Mary Sears was “entrusted with this high priority assignment.”
The November, 1943, Battle of Tarawa began the US “island hopping” campaign against the Japanese. The battle resulted in heavy casualties. Over a thousand Marines lost their lives; that was twenty percent of the Marine force. 4,690 Japanese soldiers and construction laborers died. It was the first Marine Corps battle to be captured on film. Images of dead Marines shocked audiences. The battle came to be called “Bloody, bloody Tarawa.”
What went wrong? Marines had to make their way to shore over a coral reef. To cross this reef successfully, transport vessels required a tide of at least four feet. Instead, they faced a neap, or weak, tide. “The bottoms of Higgins boats scraped across the coral reef and stopped. No boats crossed that barrier the morning of the assault … the men were stranded … had to evacuate in heavy surf.” “Troops were forced to jump into the ocean with eighty-pound packs strapped to their shoulders, hoisting their rifles overhead … while wading ashore over razor-sharp coral.” Higgins boats had been “ingeniously designed and rigorously tested. ” “Dwight Eisenhower would later credit” them as “the reason the Allies won World War II.” On this day, they “could not get to shore.”
The problem was an uncommon “apogean neap tide.” “At Tarawa, the navy had gone to war largely ignorant of this new aquatic battlefield, with its waves, surf zones, and underwater hazards.” Tarawa “laid bare the necessity for gathering as much data as possible and putting it in the hands of expert analysts.”
Of all the technological devices named in Musemeche’s book, the one that amazes me most is the analog tide predicting machine. Photos of these pre-computer computers are astounding sights. These machines were first developed by Sir William Thomson, later Lord Kelvin, in 1872-3. Americans and Brits used tide predicting machines for D-Day and Pacific landings. These machines required a “harmonic constant,” reached through manual collection of local water-level measurements over the course of several weeks. To acquire such obscure data, Mary Grier dug up material on areas not explored by Americans and previously published by the Japanese. The nineteenth-century British expedition in the Pacific of the HMS Challenger also provided invaluable data. Grier tracked down articles like “A Brief Note on the Submarine Geology of the Pacific Ocean between the Tokyo Bay and the Bonin Islands,” published in 1908 by The Journal of the Geological Society of Tokyo. When she pulled books and journal articles from the shelves of the Library of Congress, Grier was careful to put the books back exactly where she found them, and not leave them sticking out a micrometer from the shelf. Any sign that she had accessed this or that volume might communicate to a spy where America’s next invasion was to occur.
Musemeche mentions the Japanese mass suicide following the American assault on Saipan. Admiral Chester Nimitz toured the “suicide cliff” area and vowed to find a way to prompt a Japanese surrender that would not involve an American invasion of Japan that would inevitably spark similar mass suicides.
Musemeche salutes the Montford Point Marines who served in the Battle of Saipan, the first African American Marines of World War II. Given these Marines’ admirable performance, Lieutenant General Alexander A. Vandegrift said of them, “The Negro Marines are no longer on trial. They are Marines, period.”
Sears had been ordered to produce a JANIS report on Formosa (Taiwan). Ultimately, Americans decided to land on Iwo Jima and Okinawa instead of Formosa. There would not be time for a thorough JANIS on either site. “Uniquely among Pacific War Marine battles, the American total casualties on Iwo Jima (dead and wounded) exceeded those of the Japanese.” The notorious “sands of Iwo Jima” were of a type that would not allow traction. The Marines who made it to shore “sank knee-deep into the muck of volcanic ash.” “We did more crawling than anything else,” reports Bud Nardecchia, a nineteen-year-old Marine from Texas.
Harry Truman became president with the death of FDR. Only then did Truman learn of the Manhattan Project. The Joint Chiefs informed Truman that Operation Downfall, the invasion of Japan, would require five million soldiers and might result in over a million US casualties and millions of dead Japanese, including civilians. Hydro was asked to prepare a JANIS on Japan.
The team was motivated by patriotism and also by grief. Musemeche mentions Hydro members whose sons died in combat, even as the war was winding down. As Truman contemplated the previously unthinkable, Hydro, as ever, thought about things most of us never think about, like snapping shrimp and other marine life that produced sounds, similar to “the sound of screws,” that might confuse sound operators attempting to detect submarines. Arcane research alerted Sears to local challenges like the bioluminescence of some sea creatures. Such naturally produced light might reveal a boat’s wake to an overhead plane.
Truman did drop the bomb, two of them. “Upon hearing that the Japanese had surrendered, the soldiers of the United States Sixth Army, who were preparing to invade Japan, felt nothing but relief. ‘We knelt in the sand and cried. For all our manhood, we cried. We were going to live. We were going to grow up to adulthood after all,’ one veteran later remembered.” Far too many of their comrades in arms had been robbed of the opportunity to “grow up to adulthood.” Lethal Tides is a magnificent salute to their memory. We owe it to these heroes to inform ourselves of their heroism, and to allow that heroism to inspire and challenge us.
Japan’s surrender did not end Hydro’s work. JANIS reports were now used to aid in the rescue of 36,000 Allied prisoners of war held by the Japanese in 140 camps. Also, Americans could not assume that all locales were safe. Dead-enders might attack. Landings of occupation forces, even after surrender, had to be combat ready. JANIS reports aided that readiness. Musemeche’s book concludes with final notes on the post-war careers of Sears, Henry, Chase, and Grier.
Danusha Goska is the author of God through Binoculars: A Hitchhiker at a Monastery.