Canal Defence Light

Canal Defence Light (CDL) was a British "secret weapon" of the Second World War.

It was based upon the use of a powerful carbon-arc searchlight to dazzle and confuse enemy troops. A demonstration had shown that the use of a vehicle mounted searchlight both disoriented the units facing it and masked activities behind the searchlight.

The searchlight was mounted in an armoured turret fitted to a tank. Initially the Matilda tank was used replacing its normal turret with a cylindrical one containing the searchlight (the light emitting through a vertical slit) and a machine gun. This was later replaced by the US M3 Grant which was superior in several ways; it was a larger roomier tank, better able to keep up with tanks such as the Sherman and it had a hull mounted gun which was unaffected by the replacement of its normal turret with the searchlight turret.

The light could be varied in two ways to further enhance any effect.
*Addition of blue or amber filter would make the light source seem further away or closer respectively.
*the operation of a shutter would create a flickering effect.

The project was shrouded in secrecy. It was tested during Exercise Primrose in 1943 at Kilbride Bay with the result that it was determined to be "too uncertain to be depended upon as the main feature of an invasion".

Units that were equipped with CDL

The 11th Royal Tank Regiment was raised in January 1941 and designated for the CDL role in May 1941. The unit trained at Lowther Castle near Penrith, Cumberland, spent 1942 and 1943 in the Middle East without seeing action, and returned to the UK in April 1944. They landed in Normandy on 12 August 1944, and saw no action until 29 September 1944 when they were ordered to transfer all their equipment to the 42nd and 49th Royal Tank Regiments, and were retrained to operate the American LVT4 Amtrac, known by the British Army as the 'Buffalo'.

In their turn, the 42nd and 49th Royal Tank Regiments were largely inactive for the remainder of the war, when all three units were disbanded after the end of hostilities.

oviet use

The Soviet Army attempted to use a similar tactic during the Battle of the Seelow Heights. One hundred and forty three searchlights were put in place to blind the German defenders during the initial Soviet assault. However, this helped the Germans as the light was diffused by early morning mist and made useful silhouettes of the attacking Soviet formations.

urviving example

A CDL equipped Matilda tank still exists as part of the collection of the Royal Armoured Corps Tank Museum at Bovington, Dorset, in England. It is the only one of its type known to exist. There are no Grant examples.

ee also

*Leigh Light

References

Notes

General references

*cite book
last = J.F.C.
first = Fuller
authorlink = J. F. C. Fuller
title = The Second World War - 1939-45 - A strategical and Tactical History
publisher = Duell, Sloan and Pearce
series =
year = 1949
isbn =

External links

* [http://www.forces.gc.ca/dhh/downloads/ahq/ahq042.pdf Report on DDay preparations]
* [http://www.thewarillustrated.info/220/now-it-can-be-told-tanks-that-turn-night-into-local-day.asp Now It Can Be Told! - Tanks That Turn Night Into Local Day] , The War Illustrated, November 23, 1945.