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Outsmarting the Axis: How A Tiny Secret Weapon Helped Turn the Tide of WWII
A military secret on par with the Manhattan Project
On January 5th, 1943, three Japanese dive bombers, codenamed Val, surprised and attacked an Allied naval group operating off of the coast of Guadalcanal. One of the planes managed to score a hit on a New Zealand flagged destroyer. It was one of thousands of such incidents unfolding across the Pacific, and by most counts, the attack was unremarkable. As the planes were flying off, the USS Helena, an armored cruiser, launched a barrage of anti-aircraft fire toward the planes. The shells missed, but one of the planes was caught up in the flak and destroyed — despite not receiving a direct hit.
Unbeknownst to everyone in attendance that day, the crews had just witnessed the first take down of an enemy aircraft using variable time (VT) fuzes attached to the anti-aircraft shells. As the Val bomber burst into flames and fell into the sea, it marked a change in the war that would help the Allies roll to victory.
Variable time was a ruse. The shells were not working with some new advanced timer but rather a secret proximity fuze that was the result of years of engineering and secretive work. The fuzes contained over 130 tiny electronic parts and allowed the shell to explode near enemy planes, causing severe damage without requiring a direct hit.
Prior to the invention of the VT fuze, shells were timed to explode after they reached a certain altitude or when they directly struck a plane. For the first few years of World War II, most anti-aircraft fire was inaccurate and ineffective. After the Battle of Britain, the British estimated that it took between 1,500 shells or 10,000 bullets to down a single enemy aircraft. That was all about to change.
The new VT proximity fuze was the result of hundreds of engineers working in secret in labs across the United States to the tune of $1 billion. It was given the name Variable Time Fuze to confuse enemy spies and observers. Sailors and soldiers loading the new shells talked about the new timer. But it wasn’t a timer. It was a sensor.
War planners estimated that the VT fuze would increase the lethality of individual shells by five to ten times. The fact…
