The A to Z Challenge asks bloggers to post 26 posts, one for each letter of the English alphabet, in April. Most of us choose to make these posts on a particular theme. My theme for 2022 is Codebreaking in World War II, which fits with the topic of the novel that I’m writing. Visit every day (except Sunday) in April for a new post on my topic.

P is for Mary Louise Prather

This is an obscure topic for my theme of codebreaking in World War II, but I’m fascinated by Mary Louise Prather, because she’s likely related to me.

Before World War II, Prather worked, as a civilian worker for the Army, in William Friedman’s cryptology operation. She ran the office machinery, except this wasn’t ordinary machinery – it had been hacked to handle the work of codebreaking.

Prather was also in charge of the filing. That, too, was more than it might appear. The person who did the filing was the person who was most likely to be able to put her hands on the document that you needed at the moment you needed it.

Prather’s memory and organization led to a vital breakthrough on the solution to Purple, the Japanese diplomatic code, that Friedman’s team broke just before the war and proved invaluable for the duration.

Here’s what Friedman wrote about her when he recommended her for a medal:

To Miss Mary Louise Prather credit should be given for the careful keeping of the records and the index to all messages and it was as a result of her painstaking attention to detail that a paraphrased message was found which formed a very important link in the solution. (p. 2, Recommendations for Legion of Merit and Medal for Merit Awards (nsa.gov))

Before the war, Friedman’s operation was small, gradually increasing after the war in Europe began. A month after Pearl Harbor, the Army organized the Signal Intelligence Service. Mary Louise Prather was named to head the Stenographic subdivision under the Cryptanalytic unit, making her the highest-ranking woman in that unit.

She stayed on in the work after the war. Cryptanalysis eventually became the bailiwick of the National Security Agency.

Here is her short obituary from the Washington Post on 23 December 1996:

Prather, Mary Louise (Age 83)

On December 20, 1996 of a stroke. She was a Division Chief at the National Security Agency until her retirement in 1969. She is survived by her brother Elbridge Prather of Arlington, VA. A Memorial service will be at Falls Church Presbyterian Church 11 a.m. Friday, December 27.

For further reading, Code Girls by Liza Mundy tells the story of how two women, Mary Louise Prather and Genevieve Grotjan, made two of the most important leaps that broke Purple, in Chapter Three.

A Genealogy Note

One branch of my family goes through generations of Prathers. My Grandma Weese’s maternal grandmother was a Prather. According to the Prater / Prather Genealogy database, my 9th great-grandfather, Thomas Prather, who moved to the Virginia colony in 1622, is the ancestor of 98% of Prathers (and a variety of other spellings) in the United States.

So, I always perk up when I meet a Prather, since they are probably a cousin of some sort.

If Ancestry and the Prather / Prater Genealogy database are correct (I didn’t perform my usual due diligence because there wasn’t time before I wrote this post), Mary Louise Prather is my 8th cousin, once removed. Our most recent common ancestors are one of Thomas’s sons, Jonathan and his wife Lyle Jane MacKay.