Longines C.O.S.D.: Vintage Military Watch Guide

Lépine · 2023-06-13T15:04:05Z

Explore the rare Longines C.O.S.D. 'Tuna Can' and Gold Dennison variants, critical British military dive watches from WWII. Uncover their history, repurposing, and the elusive Omega C.O.S.D.

Lépine

WPS member · Horological Meandering forum

16 replies4306 views10 photos

Lépine, a distinguished member of the WatchProSite community, delves into the enigmatic world of the Longines C.O.S.D. watches. This article goes beyond typical historical accounts, focusing on the rare 'Gold Dennison C.O.S.D.' and its intriguing variants. Lépine's personal collection and extensive research illuminate the complex history and repurposing of these significant military timepieces, offering a fresh perspective for both seasoned collectors and new enthusiasts.

I thought I would do something different for a change. This post is not about the background history of a watch. This post is about the existence of a rather rare animal. It is the "Gold Dennison C.O.S.D." and other variants.

Here is my example that I have posted here before, it was an award given to William Lawson in 1947 for his life long contributions to WW1 and WW2 Wartime Agriculture Executive Committee. Etc etc, he saved the world...no he didn't...but he was really important that the King and Queen of England separately and over two wars awarded him the Order of the British Empire. No one gets this honor twice, but he did.

So typically this is the type of Longines C.O.S.D. that everyone knows about. It is nicknamed the "Tuna Case" Combined Operations Store Depot watch that was built on a very narrow date range of about May to July 1945. These all began life as just a movement, dial, and hands supplied by Longines to the Ministry of Defense for the British Navy. The Longines made dials were the radium dials as shown in the above gold C.O.S.D. The below watch actually has a MoD dial. The British Navy replaced the radioactive dials with non-radio active dials.

My watch is a bit of a Tuna mutt. It has the case of a Big Crown C.O.S.D. so it should have a radium dial, but it currently has the MoD dial and handset for a Small Crown MoD C.O.S.D.

Not many people outside of Military Watch collectors know that many of the movements from the original "Tuna" dive watches were made back into Dennison Steel watches and then repurposed. The Tuna cases were just too crude to wear everyday and there were likely a number of these C.O.S.D. that were useful the British MoD, took the movements out of the cases and put them into Steel Dennison cases. This is why over the years piles of empty Tuna cans were found. This is a typical example of a B.O.A.C. airlines issued recased C.O.S.D. An all original untouched Tuna most likely is an extremely difficult watch to prove given what happened to all of these C.O.S.D.

Okay so you have seen my gold C.O.S.D.
These next two watches are as far as I am aware and most other watch historians are aware, the only other two gold C.O.S.D. watches to have ever shown up.
There most likely were more of these, but at some point, they most likely were turned into Tunas and then the gold cases were melted so maybe only three left.

Almost forgot, the taxonomy would not be complete without noting that there were Omega C.O.S.D. as well.

The Black C.O.S.D. is considered the holy grail of C.O.S.D.

And this guy also is a bit of an enigma. A few very knowledgeable individuals in Britain have looked over the watch and documentation from Longines.

There is a possibility that this is an early evaluation model of the C.O.S.D. The size of the Tuna case inner dimensions is slightly bigger than a normal

Tuna and it is unmarked. A similar watch was (re)issued in 1950 to a British soldier. We don't know if this is the same watch.

Key Points from the Discussion

Longines' official extracts do not explicitly state 'C.O.S.D.' because the brand sold movements, dials, and hands to the UK Ministry of Defense, and was not privy to their subsequent casing and deployment.
The research on C.O.S.D. watches is an ongoing project, frequently reviewed and updated by experts at the Military Watch Resource (MWR) forum, ensuring accuracy and incorporating new discoveries.
The Omega C.O.S.D. is exceptionally rare, with only about four recorded examples, making its discovery a significant event within the collecting community.
C.O.S.D. watches were definitively dive watches, intended for commando divers clearing beach obstacles, a fact supported by photographic proof in the Imperial War Museums, dispelling common misinformation about their use by paratroopers.
The scarcity of original, untouched 'Tuna' C.O.S.D. watches is due to the British MoD often recasing movements into more durable Dennison steel cases, leading to many empty 'Tuna' cases being found over the years.
Acquiring a Longines C.O.S.D. is challenging due to their expense and the prevalence of 'frankenwatches'; it is advisable to seek older, recorded examples with confirmed extracts from May-July 1945.

The Discussion

Dr No

Jun 13, 2023

. . . which I've never seen before. I wonder how many were made. Stunned, Art

LÉ

Lépine

Jun 13, 2023

This is an ongoing project and is frequently reviewed by members of the Military Watch Resource MWR which is It's regularly viewed by thousands of people so most likely pretty up to date. They tell me when I get it wrong :p Hummm, can't seem to get it to display full size here... The Omega C.O.S.D. is very rare. I have only recorded about 4 of them. Okay...maybe the link to the thread on MWR will help. Not able to get it to display correctly. www.mwrforum.net

Dr No

Jun 13, 2023

. . . please let me know!

LÉ

Lépine

Jun 13, 2023

Just these three are mine. The "prototype", gold, and Tuna mutt. More pictures of other peoples Omega C.O.S.D.

LÉ

Lépine

Jun 13, 2023

When people find one, all hell breaks loose and it is an Internet Party! This one was just found! Look at that radium burn from 80 years of sitting somewhere. No one cares if id even runs!! It's just such a rare and one of the first Commando watches in history! So COSD were dive watches. This is a fact. There's been so much misinformation about paratrooper and Operation Market Garden etc etc. These were divers watches. There's proof in the IWM. Solid photographic proof. The watch below shows ra

Mr.Gatsby

Jun 13, 2023

My close encounter with one of these tuna cans was in HK a month or two ago: Best Gatsby

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Longines C.O.S.D.: Vintage Military Watch Guide

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