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The 20th PID Book combines original photographs, reports, maps, and memories with modern context to illuminate the vital work of WWII photo interpreters. What did the original 1945 volume mean to your father, Lt. William J. Snodden, and to your family?
I can’t remember my dad ever talking about his experiences during the war when I was growing up. It was only when he was in his late 80s, and I asked him specifically about those years, that he pulled out his military papers and this commemorative album. That day was the first time I heard about his work as a photo interpreter. Dad was never one to show his feelings, but as I watched him reverently page through the book, I could tell how meaningful that time was for him. My mom was a master declutterer, and as they moved from their family home to increasingly smaller senior apartments, she was ruthless. The fact that the album and his military records survived those repeated purges testifies to how important they were to him.
In 2019, a few months before he died, we donated the album to the Arizona Commemorative Air Force Museum in Mesa, Arizona. It was hard for him to give it up, but he was clearly glad to see it in a place where it would be preserved for future generations. I know he’d be pleased that I’m now making its contents available to people outside the museum.
What was the role of the 20th Photo Intelligence Detachment during World War II, and why do you think the work of photo interpreters remained relatively unfamiliar compared with other forms of wartime intelligence?
When I’d mention the book to friends as I was working on it, their first question was always, “Oh, was your dad a pilot?” The pilots who took the aerial photos have received a lot of well-deserved attention in history, but without the men developing and interpreting those photos, all of that information would have been for naught.
With each sortie, the reconnaissance pilots came back with hundreds of images. The PIs often worked throughout the night, first developing the photos and then, hunched over tables and peering through stereoscopes at minute images, identifying potential bombing targets, assessing whether attacks had successfully destroyed those targets, and annotating photographs before summarizing their findings in typed reports. As many as a hundred copies of a report could then be produced for distribution to commanders. During the height of the war, all of this was accomplished in less than twelve hours!
On the surface, the work of the PIs might appear dull and isn’t likely to attract the attention of a major motion picture studio. Their success wasn’t dramatic or especially visible—their product was intelligence. Pilots flew dangerous missions in recognizable aircraft; PIs worked behind tables with stereoscopes, pencils, photographs, and typewriters. One photographs beautifully. The other doesn’t. Yet both were part of the same intelligence chain. Accurate and timely tactical intelligence allowed commanders to make the best use of their resources, disrupt German activity, and ultimately save resources and lives.
The original book contains humor, cartoons, personal memories, and photographs alongside technical intelligence. Why was preserving their personalities and everyday experiences as important as documenting their military work?
This album was created just before the men were released from duty. It was created by the men of the unit, for the men of the unit. It shows us how they chose to remember that time in their lives and could also serve as a way to share their wartime experiences with family and friends. By adding humor and cartoons, they turned their work into stories.
The route map, in particular, contains more than 30 vignettes of locations and events throughout Europe. Some pertain to large-scale wartime events, like the liberation of Paris, while others show experiences specific to the 20th PID, like their crossing of the English Channel in a small boat stuffed to the gills with soldiers, a jeep precariously balanced on the bow, and a nearby periscope watching from the deep.
An ex-soldier could use that tiny drawing as a prompt: “Oh, let me tell you about THAT day!”
Eighty years after the original book was created, what do you hope publishing this restored edition preserves for the next eighty years?
Most, if not all, of the men in the 20th PID are now gone. This book is a uniquely creative artifact documenting firsthand their work and experiences during the war. I would like future generations to know of their contributions through the men of the unit themselves.
The book also has a place in military history. Although aerial photo interpretation had been used before WWII, during the war it became increasingly sophisticated and systematic and was integrated into fast-moving tactical operations.
What makes this book unusual is that we don’t have to reconstruct that process eighty years later. The men themselves left us the photographs they examined, the reports they produced, the maps they used, the cartoons they drew, and their own explanation of what they did.
My hope is that eighty years from now, another reader can open this book and still hear their voices.
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The 20th PID Book: A Rare Look at a WWII Photo Intelligence Detachment
Nancy Finston’s The 20th PID Book is both a restored wartime artifact and an accessible account of a specialized intelligence unit whose work helped guide Allied air operations in Europe. The volume is based on a commemorative book created in 1945 by members of the U.S. Army Air Forces’ 20th Photo Intelligence Detachment, then expanded by Finston with explanatory notes, enlargements, historical context, and material from the military archive of her father, Lt. William J. Snodden. The result has an unusual immediacy. Readers encounter the original photographs, cartoons, reports, maps, and recollections while also receiving enough explanation to understand the technical language and procedures behind them. As the introduction puts it, the book functions as “both a historical artifact and a working record,” a description that accurately captures its distinctive character.
The book is strongest when it shows photo intelligence as a process. Its detailed “Life Story of a Sortie” follows reconnaissance photographs from the aircraft through film processing, mapping, stereoscopic interpretation, reporting, bombing, damage assessment, and archival preservation. That structure makes the work of the detachment tangible. Aerial images were compared with earlier photographs, matched to coordinates, examined for minute physical changes, and annotated so that commanders could act on the findings. In some cases, the entire process from receiving developed photographs and a pilot’s trace report to distributing intelligence to headquarters took “LESS THAN 12 HOURS!” Later chapters reinforce that sense of precision by showing bomb damage reports, target studies, pre-strike and post-strike photographs, and ground photographs that confirmed the interpreters’ assessments. The accumulated evidence gives the reader a clear understanding of how observation became actionable military intelligence.
Finston also succeeds in preserving the human character of the original keepsake. The technical material is balanced by cartoons, personal recollections, photographs, a humorous route map, commendations, and the commanding officer’s farewell letter. These elements show the detachment as a community of young servicemen as well as an intelligence organization. The route map is particularly effective because it transforms the unit’s movements from England through France, Belgium, and Germany into a visual diary filled with mud, restricted cities, makeshift quarters, danger, and moments of relief. The closing material deepens that personal dimension. Major Frederick Ahlson’s 1945 letter recalls the men who had “lived, worked, wined and dined together” and expresses the hope that their wartime friendships would survive their dispersal. Because these voices and images come from the unit itself, the book conveys memory at a scale that conventional operational histories rarely capture.
The 20th PID Book is a carefully assembled archival history of the people, methods, and wartime responsibilities of the 20th Photo Intelligence Detachment. Its value lies in the way it connects technical intelligence work to specific military consequences, from identifying hidden landing grounds and supply dumps to assessing damaged bridges and transportation networks during the Allied advance. At the same time, the restored keepsake preserves how the men chose to remember their own service after the fighting ended. Finston’s editorial additions generally serve that original material well by explaining unfamiliar practices without overwhelming the firsthand record. The book should appeal to readers interested in World War II, military intelligence, aerial reconnaissance, archival history, and the less visible forms of expertise that shaped battlefield decisions. It preserves a specialized chapter of the war with clarity, documentary richness, and a strong sense of the individuals behind the reports.
Pages: 140
