Dr. Mary Sears and the Forgotten American Servicewomen Who Helped the U.S. Win in the Pacific

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Twenty years before the Navy would make use of her extraordinary knowledge of the sea, Mary Sears was an undergraduate at Radcliffe College. There, she spent most days at Harvard’s Museum of Comparative Zoology, studying marine invertebrates. Sears, then a short, bespectacled, and unassuming young woman of twenty-two, was enamored with the work she was doing. She was a born scientist, fascinated by amphibians—frogs and salamanders in particular—from a young age. In her youth, she frequently waded into Heard Pond of Wayland, Massachusetts, where she grew up, looking for critters.

By 1933, her childhood love of amphibians had blossomed into a career, culminating in a doctorate from Radcliffe, her third degree from the institution, with a dissertation titled “Migration of Pigment in Frogs’ Eyes.” While completing her doctoral work, she had studied under the most celebrated oceanographic scholars, including her advisor, Henry Bryant Bigelow, and other men who were building the oceanographic field from the ground up. The field’s growth was also being spurred by the Navy’s interest in it, since the sea-based services realized they would be major beneficiaries of a deeper and more scientific understanding of the ocean, especially as the crisis in Europe and the Pacific unfolded.

By the time the Navy was deep into its planning for amphibious assaults in the Pacific, Sears had moved to the Woods Hole Oceanographic Institution (WHOI) in Cape Cod, Massachusetts, where she was working with a small but growing number of oceanographers. The “Harvard Yacht Club,” as the WHOI team was known, was being propelled by a gifted, creative, and motivated band of scientists, of which Sears was a central figure. While there, she had made a name for herself, and the Navy took notice.

By the end of 1942, the Navy’s Hydrographic Office (Hydro) had gutted WHOI of its most talented scientists to assist them in coordinating the expanding oceanographic research and in creating the maritime charts for the Pacific campaigns. Sears had been recruited from WHOI in December 1942 by the head of the Hydro, and by February she had been appointed as an officer in the WAVES and posted there. 

The office was responsible for creating and distributing up-to-date navigational charts “to afford the maximum possible navigational safety and facilities to ships on the sea and to aircraft operating over sea routes.” This special mission, which the office had been doing since 1866, had suddenly become much more urgent and demanding with the onset of hostilities. The uptick in Navy activity in the Pacific threatened to overwhelm Hydro as it struggled to keep up with the demand for new, detailed, and accurate navigational charts and memoranda to guide the transport and invasion forces scattered across the sea and sky.

By the time Sears arrived on the scene, Hydro had been moved under the Chief of Naval Operations, a reflection of its growing importance in the unfolding war in the Pacific. Personnel had grown somewhere between two hundred to five hundred percent for months, and 13 million charts and publications had been printed in 1942 alone. Most Hydro sections were working in two shifts to provide near-constant coverage, and where possible they had three. But the demands never ceased, and Hydro had trouble retaining personnel as their civil service staff was lured away by job opportunities in the military and industrial sectors. They began requesting the Navy’s personnel and resources to fill the gap.

Midway through the war, however, nearly every Navy office was competing to fill personnel gaps. Hydro stood little chance of securing the complement of trained, low-ranking, enlisted men they had requested to help meet their requirements. Instead, the Navy offered them seven officers and ten enlisted women from the WAVES.

The WAVES quickly proved their worth. Within a month, Hydro’s air navigation branch requested ten more WAVES; a year later, Hydro estimated it needed three hundred. The women worked as stenographers, draftsmen, IBM operators, lithographers, and multilith operators, and often trained on the job for more advanced tasks. Karen Berkey, for instance, was among the WAVES assigned to Hydro. She had been selected for her artistic skills, which were critical for creating the highly classified naval and aviation maps used by sailors and airmen in the Pacific. In a letter home, she noted that she could not share much about her work given its highly classified nature: “I’m not allowed to say much about what I’m doing because it’s too vital and important and secretive,” but she did confide that she had been assigned one of the most difficult art jobs in the unit, adding, “I confess I was terrified at all of the complications.” Every member of the Hydro team, from Sears to Berkey, knew the work they were doing, no matter how technical or tedious, was essential to Allied progress in the Pacific.

Within six months of her arrival, Sears was promoted to director of the Oceanographic Unit, having been handpicked to oversee the ceaseless requests for oceanographic intelligence that swamped the office. Working with a combined section of Army and Navy personnel, she and her staff were charged with helping the Navy figure out where to land their ships. “In view of the probability of amphibious operations in many theaters,” read a joint Army and Navy intelligence study, “it is of importance to compile and disseminate, as soon as possible, information on average sea and swell conditions, surf characteristics, tides, tidal and other currents, bottom material, probable underwater sound conditions and similar data.” They secured that information from Sears.

On paper, their task seemed straightforward: translate academic oceanographic studies into useful insights for military commanders planning their operations in the Pacific and Indian Oceans. Sears and her team were asked for, and expected to provide, information on “ocean currents, wave and tide predictions, amphibious landing sites, and presence of propeller-fouling kelp or bioluminescent marine life.” But the group lacked up-to-date information for many of the requests they received, forcing them to rely on whatever material they could obtain, pulled from all kinds of sources. Whether it be a fifty-year-old Dutch publication, a prewar Japanese survey published in an academic journal, information collected by a Navy survey vessel, or, in some cases, pure guesswork, Sears and her team were expected to use the limited information they had to provide accurate predictions.

Even in the face of these constraints, however, Sears and her team found ways to provide surprisingly precise assessments for naval commanders. Having spent her entire career developing the field of oceanography from scratch, Sears was accustomed to challenges like the one facing the Navy, and she thrived in the environment. Sears’s first project, a study of the drift of debris and small rafts in the Atlantic and Pacific undertaken at the behest of Congress and completed entirely on her own, became the authoritative guide for rescuing pilots, crews, and ships that crashed or were sunk in naval combat and oversea flying. The intelligence provided by Sears and her team was not perfect, but it was far better than the paltry information that the Navy had relied on in the early days of the war, and the demand for her team’s reports only grew.

As Sears’s team and know-how expanded, her work became increasingly consequential. By 1944, Hydro was working on joint intelligence reports that broke down the key characteristics of military targets across the Pacific—including Sakhalin, the Kurils, Hokkaido, Palau, the Marianas, Java, Makassar Strait, Cam Ranh Bay, and the Singapore Strait—all areas the US Navy planned to land or transit in during the next two years. These comprehensive reports took up most of her team’s time and focus, but Sears also recalled having to divert attention to urgent matters on the fly, often after a meeting of the combined British and American leadership. These quick-turn taskings were sometimes so secretive that only Sears was cleared to work on them, but she never failed to complete the expert analysis, even if it meant she worked overnight, alone, and exhausted.

The WAVES assigned to Sears’s unit were inspired by her expertise and dedication, and eagerly followed her example. Sears’s late nights and relentless pursuit of the answers to seemingly impossible requests told the WAVES at Hydro everything they needed to know about what would be expected of them. “It does feel good,” wrote Berkey in a letter home, “to know my work is essential, that an error on my part would be drastic, and that my good work means victory is that much closer.

“That is absolutely all I can say about Hydro,” she warned.

Excerpted from the book Valiant Women: The Extraordinary American Servicewomen Who Helped Win World War II by Lena Andrews. Copyright © 2023 by Lena Andrews. From Mariner Books, an imprint of HarperCollins Publishers. Reprinted by permission.

Lena Andrews is a military analyst at the Central Intelligence Agency. A Boston native, she received her Ph.D. in political science from the Massachusetts Institute of Technology, specializing in international relations and security studies. She has spent more than a decade in foreign policy, having previously worked at the RAND Corporation and United States Institute of Peace. Lena lives in Washington, DC with her husband and son, and is always looking for fresh takes on old stories. Valiant Women is her first book