Now You Know Part 3 of 7

Dahlgren: A Bubbling Cauldron of Technical Curiosity, Segment 3 of 7

By Alan J. Dean

World War II – The Flames under the Cauldron are Fanned

As the dark storm clouds of World War II approached, Dahlgren began a dramatic expansion. Additional land was acquired for a railroad to Fredericksburg. It established the Anti-Aircraft (AA) Fuse and Machine Gun ranges, and in 1944, the station acquired the Pumpkin Neck Test area, expanding the Base size in excess of 5,000 acres.

The experimental officer at Dahlgren, LCDR William “Deak” Parsons recalled “by 1940 after the fall of France, we at the Proving Ground began to receive enthusiastic [scientific] groups first with ideas to discuss and then with gadgets to test.” The airplane’s role in combat had expanded significantly since WWI. With their speed, agility, and ability to deliver ordnance more accurately, they had become an effective weapon against ships. Anti-aircraft weapons of the time had very little chance of a direct hit and even the addition of clock fuses did little to improve these chances. Something new and radical needed to be built to defend against this threat.

One of the visitors to Dahlgren had been researching using different technologies to create a “proximity fuse” that would “sense” the target and trigger the ordnance. These “fuses” were first tested using bombs because of the bomb’s size to hold the technology and the relative benign delivery of such ordnance compared to firing from a gun. However, Parsons recognized that such a technology would be much more effective if it could be placed in a gun shell. Development and testing began, and by 1941 Parsons had demonstrated at Dahlgren that a radio proximity fuse could survive being fired from a 5-inch gun and still be working 5 miles down range. By January of 1943, Parsons was in the Pacific theater for a combat test of the “proximity or variable timed (VT) fuse.” With one round the USS Helena downed a Japanese observation plane, thus demonstrating the first use of a “smart” weapon. The VT fuse is considered one of the technologies that helped win the war. LCDR Parsons went on to be assigned to Project Y, part of the Manhattan Project, developing the fuse of the first atomic bomb, work that was also performed at Dahlgren.

LCDR William “Deak” Parsons (U.S. Navy Photo)

During WWII, workforce rolls swelled from 254 in January 1939 to nearly 1,500 by July 1944.  Most of the workers were women. The members of the Women Accepted for Volunteer Emergency Service (WAVES) were posted to many of Dahlgren’s military positions. Their jobs ranged from data collecting and analysis during proofing of ammunition and guns to performing the complex computations by hand to produce Tables of Ballistic Correction factors for each type of gun and ammunition. By 1945, Dahlgren’s guns were firing an average of 5,000 rounds per week. The Potomac River Test Range worked 24 hours a day, seven days a week, until the end of World War II.

Waves in Front of Building 183 in 1943 (U.S. Navy Photo)
Collecting Data During Gun Firings (U.S. Navy Photo)

After the war, the guns fell eerily silent as post war Dahlgren life returned to peaceful existence, and the flames under the cauldron turned to embers. The flames were again fanned during the Korean War. By 1954, quiet returned and the flames began to die once again, raising questions as to whether Dahlgren had become obsolete. What was unseen was that the kindling of activities and technology added during WWII had begun to ignite and fuel a transformation of Dahlgren’s mission.

The New Kindling Ignites

The work to accurately create the Tables of Ballistic Correction factors was time-consuming and tedious. In October 1944, the Bureau of Ordnance authorized a contract with Harvard University for the design and construction of a controlled sequence calculator, to be designed and built by Dr. Howard Aiken for the proving ground. It was estimated that this “calculator would be able to perform the work that 10 people did in an hour to mere seconds.” In February 1945, Dr. Aiken and his team at Harvard, which included LT Grace Hopper, began building a new electro-mechanical, sequence-controlled calculator, called the Aiken Relay Calculator Mk II, under the contract to Dahlgren. Because of the promise of this technology, the work on Mark II continued after the conclusion of the war. The machine required considerable troubleshooting, and during final testing for shipment to Dahlgren in September of 1947, a problem occurred. In diagnosing the problem, Bill Burke, a technician who moved to Dahlgren with the computer, discovered a moth caught in one of the relays in the machine. He removed the moth, and the machine performed the program without error. Many still believe that this event was what coined the term “de-bugging” a computer. However, as Ken Jennings stated in his Blog from 2017, “As early as 1878, Thomas Edison was writing to an inventor colleague about bugs.” The term “bug” had been associated with machinery and systems since at least that time. The one fact that remains, though, is that this was the only documented case of an actual bug being removed from a computer, becoming a unique footnote in Dahlgren history.

Moth Found in MK II Computer (U.S. Navy Photo)

With the arrival of the Mark II, Dahlgren added the kindling that would fuel its expansion for the next 50 years.

About The Author

Alan Dean is a member of the Dahlgren Heritage Museum dedicated to preserving Dahlgren Base history. He worked at Dahlgren from 1974 to 2017. He wishes to thank Ed Jones, Dr. Rob Gates, Bob Dibble, Peter Kolakowski, and Bill Elliott for their reviews and comments on this article.


Previously published – Northern Neck of Virginia Historical Magazine, 70th Anniversary, December 2020, King George County, Virginia, 1720-2020 published by The Northern Neck of Virginia Historical Society MONTROSS, Westmoreland County, Virginia –

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