An 8.5/8.8 cm Flugabwehrkanone M39(r) in Holland

I've known for a while that the Vesting Museum (fortress city museum) in Naarden, the Netherlands, had a World War Two anti-aircraft gun in its collection. I shot a picture of it two weeks ago and back home tried to identify the gun.

The gun on August 20th, 2022. Shot with A Pentax 645 fitted with an SMC Pentax-A 645 150mm f/3.5 lens, loaded with Fomapan Profi Line Classic 100/120 film, developed in Adonal and scanned with an Epson Perfection V850 Pro.  

At first glance it looks like a regular German 8.8 cm Flugabwehrkanone (FlaK). Whilst this gun generally looks the same it is however something entirely else. It is of Soviet origin but, as it turns out, with German DNA.

I knew of its Soviet origins from an earlier visit to the museum so that is where I started my research. Now the Soviets in the 1930s developed three models of anti-aircraft guns:

The first model was the 76-мм зенитная пушка обр. 1931 г. (3-К) or 76 mm M1931 air defense gun. The model 1931 was based on the Rheinmetall 7.5 cm Flugabwehrkanone L/59. Through the BÜTAST agency the Soviets bought four prototypes and the design drawings of the 7.5 cm FlaK L/59 in 1930 and used these as a basis for a 76mm anti-aircraft gun that would be known as the 3-K or model 1931 in service, named after the year it was introduced in service. It was a towed gun and used the ZU-29 two-wheeled mount with four legs, two of which could be folded during transportation.

After about 4,550 3-Ks were produced between 1932 and January 1940 production was halted after the introduction of the 76-мм зенитная пушка обр. 1938 г. or 76 mm M1938 air defense gun (no K designation). This was the same gun as the 3-K but fitted to a different mount that was quicker when changing from the transport-mode to the firing-mode. This was the four-wheeled ZU-8 mount. About 960 M1938s were built in the period 1938-1940. The reason no more were produced was that work had also started on an upgunned variant of the M1938, fitted with a 85mm barrel.

This was the 85-мм зенитная пушка обр. 1939 г. (52-К) or 85mm M1939 air defense gun (52-K). The first prototypes were built in 1938 and it was in production from 1939 until 1945 with a total of about 13,422 guns produced. During the early years of World War Two all three models were used but quickly the M1939 replaced all preceding models on the front line.

Now this is where it becomes interesting as all these guns look very similar. The main difference between the M1931 and the M1938/M1939 is the mount (ZU-29 or ZU-8) and the main difference between the M1931/M1938 and the M1939 is the bigger 85mm gun barrel on the M1939. This bigger barrel also has a larger muzzle brake and that in particular is a distinguishing feature.

The gun on August 28th, 2022. This was shot with a Pentax 645Z fitted with an SMC Pentax-FA 645 Zoom 45-85mm f/4.5 lens, as are all following photographs.

Whilst the few shots I took gave a great overall impression I decided to go back and this time take some more detailed shots in order to determine which of the three models was on display. This is what I discovered:

First: The serial number of the gun is 3273. This confirms the actual identity of the gun but as I'm not aware of any serial number listings I can't deduce the model from it.

Serial number 3275, built in 1938.

Second: The year of manufacture is 1938. Again this does not rule out any of the models because the M1931 serial production was from 1932 to 1940, the serial production from the M1938 was from 1938 to 1940 and by 1938 the first prototypes of the M1939 were produced.

The ZU-29 mount. This is where the weels would be attached.

Another look at the ZU-29 mount.

Third: The gun mount is a model ZU-29. Now this was only fitted to the M1931 model.

Fourth: The gun barrel has the bigger muzzle brake that was only fitted to the M1939 model.

Fifth: During the war the Wehrmacht captured loads of M1931s, M1938s and M1939s on the battlefield and put them to good use themselves. Most of the captured guns were modified to take the same 88mm shells the dreaded 8.8 cm Flugabwehrkanone used and according to the museum staff this is one such example. Furthermore, in a 2020 tweet from former museum director Bas Kreuger he mentions that the museum traded the 'Russian M35/85' with the Overloon War Museum. He adds that the gun has a pre-production barrel.

Sixth: I also emailed the Vesting Museum about the origins of the gun. Current museum director Tammo ter Hark wrote back, stating that this is an 'M85' that they have on loan from the Overloon War Museum and that it arrived about ten years ago.

Another view of the 8.5/8.8 cm Flugabwehrkanone M39(r)

So what model is it? My conclusion is that this is in fact a German upgunned Soviet 85-мм зенитная пушка обр. 1939 г. (52-К) or 85mm M1939 air defense gun (52-K) based on the fact that the gun itself has the bigger muzzle brake. The fact that both museum directors talk about an '85', probably referring to the caliber 85mm and that Bas Kreuger mentions the pre-production barrel support this conclusion. That the gun is mounted on the older ZU-29 mount is odd, but this could have happened either during or after the war. The German designation for an M1939 converted to 88mm in Wehrmacht use is 8.5/8.8 cm Flugabwehrkanone M39(r) with the (r) standing for Russia, indicating that this is a beutewaffen or captured weapon. It came from the Overloon War Museum, a museum that was created in 1946 with a collection that consisted of weaponry that was left behind after the 1944 battle of Overloon. This would make the museums 8.5/8.8 cm FlaK M39(r) a veteran of this battle. It is fair to assume that this gun was also used as an anti-tank gun in this battle, much like the Germans used their own 8.8 cm FlaK guns against tanks. A 1965 video shows this gun at the Overloon museum.

All in all this makes for a very interesting exhibit in the Vesting Museum. But why is it displayed there? The answer to that lies in the same Twitter message from former director Bas Kreuger. He reacted to a tweet from Klaas Meijer, in which Klaas speaks about the remains of a bunker complex formerly used by the Kriegsmarine Lehrbatterie Naarden (naval training battalion Naarden). Here Kriegsmarine personnel manning the Atlantic Wall were trained on the 8.5/8.8 cm Flugabwehrkanone M39(r) and similar 10.5 cm FlaK guns, shooting at targets over the IJsselmeer (Lake IJssel). This gun was brought to the Vesting Museum to tell that story.