Join UsBecome A MemberDonor Recognition
The Asdic Sonar Device


Magical Castle became hub of secret war activities

World War II was marked by cunning espionage on both sides. Knowledge of battle plans and new devices was the currency of the day. It is doubtful however that enemy spies would have thought to look in the stables of the fabled Casa Loma for a magic sonar device called ASDIC.

ASDIC, named for its inventors, stands for Anti-Submarine Detection investigation Committee. This early sonic apparatus was invented around 1941. It was a predecessor to today's sonar systems. ASDIC could detect a U-Boat at a distance of five miles. At even the distance of miles the device could calculate 4 the sub's depth to a foot, its distance to within a few yards, its speed to within a fraction of a knot and its course to a degree. Such technology enabled Allied navy vessels to search and destroy fleets of enemy submarines.

William Corman viewed fantasy castle as perfect site.

The original production site for the ASDIC device in London, England had been bombed during the blitz. The Canadian production of the device was placed into the hands of William Corman Engineering Company Ltd. Sabotage was a real danger so Corman had to choose and assembly site that would not be suspected by the enemy. The site also had to have high ceilings and ample floor space. Casa Loma which was a well-known tourist attraction presented itself as the perfect spot.

"Sorry for the inconvenience"

Security experts today would have shuddered had they seen the one dollar padlock which was all which stood between the public and the secret operations. Stragglers from Casa Loma tours were kept away from the carriage room by a polite sign which read "Construction in progress. Sorry for the inconvenience." Little did anyone, including the City of Toronto, know just what was being built. When Corman made his clandestine arrangements with the Kiwanis Club of Casa Loma, it was with the understanding that the local government was not to be made aware - the project was too crucial to the Allied war effort to be placed at risk.

Many Canadian vessels were outfitted with an ASDIC device during the second World War. HMCS Haida that is now docked in the Toronto harbour near Ontario Place was one such ship. Today visitors to the HMCS Haida can see the basic components of the ASDIC device on display.

Casa Loma has its own tribute to he ASDIC device on the third floor of the Castle along with other noteworthy military displays and the Queen's Own Rifles Regimental Museum.

The ASDIC project continued in Casa Loma from 1941 until the end of the war. Sir Henry, ever the loyal military man, would have been proud had he known the integral part that his dream castle played in the World War II victory of the Allied Forces.