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WWII: How Canadian scientists decoded a Nazi war machine

August 1943: Nazi Germany unveils a new weapon that turns Allied battleships into fish in a barrel. Two Canadian scientists need to find a way to stop the bombs, and they need to do it fast.

Remotely-controlled glide bombs were a precursor to the modern drone

August 1943: The Canadian crew of the HCMS Athabaskan wasn't expecting to see a bomb change direction mid-air.

But during an anti-submarine patrol in the Bay of Biscay off the north coast of Spain, that's exactly what happened.

The terrified crew had spotted a brand new weapon from Nazi Germany, one that could attack Allied battleships with never-before-seen precision.  

These "glide bombs" were remotely-controlled — via joystick — from the planes that dropped, then guided them to hit the Allied ships.

The new weapons threatened to wipe out the entire Allied navy: it only took two to sink a battleship. In one early glide bomb attack, the Athabaskan was badly damaged and the HMS Egret (a fellow British ship) was sunk, killing 197 troops.

Despite the power and threat of these high-tech (for the time) new weapons, many Canadians at home had no idea they existed. In secret, Canadian technologists sprung into action to develop a counter-defence that would end the carnage at sea.

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There's more than one way to sink a ship

Canadian daredevils could choose from a wide range of dangerous occupations in 1943. Among the most treacherous: sailor in the Royal Canadian Navy.

Working on a ship at wartime always carries an inordinate number of threats, but Nazi Germany raised the stakes with the development of radio-controlled glide bombs — precursors to the modern drone, dubbed "ship killers."

Appearing in two flavours — the Ruhrstahl SD 1400 (or 'Fritz-X') and the Henschel Hs 293 — the missiles were designed to devastate warships and sink supply and escort ships.

Dropped by planes at a great height, far from the danger of a ship's anti-aircraft guns, the bombs were remotely controlled through radio signals sent to spoilers attached to their rear.

This turned ships (typically tricky targets) into proverbial sitting ducks.

Glide bombs ... introduced the idea of precision-guided weapons into modern warfare.

This threat to wartime shipping operations was so great that, according to author Martin J. Bollinger, the existence of radio-controlled glide-bombs was largely hidden from the public.

Glide bombs were a rudimentary precursor to the modern military drone we know and fear today. Modern drones are full aircraft, decked out with cameras, infrared imaging and laser-guided missiles. Using satellite technology, they can be controlled from thousands of miles away. Glide bombs were much simpler, but they introduced the idea of precision-guided weapons into modern warfare.

To control a glide bomb, a bombardier in the very plane that dropped the bomb would hang over the plane's bomb sight and use the missile's smoke trail to guide him to the target.

Physicists to the rescue

As soon as glide bombs appeared, physicists across the Allied world lept into action.

In Canada, the National Research Council (NRC) had exploded into a de facto military science factory, working in tandem with similar organizations in Great Britain and the United States. The NRC was founded in 1916 to advise the government on scientific and industrial research matters during WWI.

Among several NRC departments was the radio branch. Team leaders W. C. Wilkinson, physicist, and 26-year-old radio engineer (and Queen's University grad) Richard Rettie were given the crucial task of stopping glide bomb attacks — and stopping them fast.

The duo turned to radio jamming, a relatively new field of physics. They believed they could cause the German missiles to go awry by jamming the radio signals, disrupting communication between the aircraft and the bomb.

By emitting a stronger radio signal at the same frequency and modulation of the German Kehl transmitter, they essential blasted a channel with louder noise so the plane and bomb couldn't "talk."

They dubbed their device — developed in under two months —the Canadian Naval Jammer (CNJ).

It wasn't the best, but it was the first

Most of the Allied powers were working on radio jammers. While the CNJ wasn't one of the best, it was one of the first effective ones, says naval history expert David Zimmerman.

The CNJ sent a powerful jamming signal to a wide swath of radio frequencies, taking a shotgun approach to the puzzle.

On at least one occasion, Allied ships requested a Canadian ship refrain from using its CNJ, as it could disrupt their own military communications.

The jammer would automatically defeat the glide bombs' receivers, regardless of which radio frequency had been selected for an individual missile. Inelegant as it was, it was effective. More importantly, it was produced quickly. The Royal Canadian Navy sent an urgent request to the NRC for radio jamming devices on February 5, 1944. The NRC shipped the first operational CNJ to Halifax before the end of March.

Later jammers produced by the Americans and British could scan glide bombs and target their specific radio frequencies. The scattershot method of the CNJ could prove a hindrance: on at least one occasion, Allied ships requested a Canadian ship refrain from using its CNJ, as it could disrupt their own military communications.

Glide bombs went from a 30 per cent success rate to 0 per cent in less than a year

D-Day, the largest seaborne invasion in history, would have proved impossible without the CNJ and the other Allied jammers.

By April 1944, just months after the Navy had requested them, this panoply of jammers had made German glide bombs almost entirely inaccurate. They went from a 30 per cent success rate in damaging ships in September 1943 to effectively zero by D-Day (June 6, 1944), when the Allies employed at least seven different makes of jammer.

In addition to aiding D-Day and indirectly (spoiler alert) helping turn the tide of World War II, the development of the CNJ proved – as did the Royal Canadian Navy's game-changing Canadian Anti-Acoustic Torpedo (CAT) gear – Canada was capable of producing effective naval defences on a ridiculously short timeline.

The wartime NRC assisted in developing a number of other military innovations, such as the explosive RDX (like TNT on steroids), the proximity fuse and submarine detection technologies. Following the war, the NRC — like so many other Canadians — returned to civilian duties. Many of its military wings spun off or were folded into other government organizations.

Today, the NRC works with thousands of Canadian companies to help bring scientific research from laboratories to practical application.

The HCMS Athabaskan, tragically, was torpedoed and sunk less than a year after surviving its first glide bomb attack, a catastrophe that cost 128 sailors their lives. And the fates of the men behind the CNJ — Wilkinson and Rettie — have, like so much of Canadian history, been lost to time.

Watch Canada: The Story of Us on CBC and the CBC TV app: premieres March 26, 2017 at 9 p.m. (9:30 NT)

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