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1945-01-28 The Loss of Cor Kooij Spitfire RK840

Crash site: assumed to be 05.2216E/52.0233N, 300 meter Northeast of 'Huize De Ruiterberg', Doorn, Utrecht, NL

Crash cause: assumed to be hit by debris of exploding bombs dropped seconds earlier by a leading attacker


Kooij, Cornelis

C. Kooij Source: SLH Grebbeberg 090204 Kooij C


Sergt Maj Vl, F/Sgt.

RAF VR 1814967


None known




Sneek, Friesland, NL


RAF 322 (Dutch) Sqn Fighter Command




Spitfire Mk. XVI Nr. RK840 3W-M


RAF Woensdrecht, NL


Attack on 'Huize De Ruiterberg', Doorn, NL, a German sabotage training school; take-off 15.20h


KIA, aircraft hit by debris of blast of bombs dropped seconds earlier by one of the other Spitfires






300m NE of 'Huize De Ruiterberg', Doorn, NL, almost on top of the Ruiterberg in the Kaapse Bossen East of Doorn


Initially buried 30/1/1945 as unknown in Doorn General Cemetery, NL. Identified 18/3/1945, and his name was written on the cross. Reburied 14/7/1972 Militair ereveld Grebbeberg, Rhenen, NL, grave 9/1. Source: Henk Welting

Known to






Credited with 3 V-1's shot down


St. George's Chapel, Biggin Hill

GB arrival

Came from ML-KNIL. Trained at JAAB, USA, and send to GB



According to Lutgert/Sorgedrager, 1993, he was killed by a premature explosion of a bomb

"De aanval op de opleidingsschool voor saboteurs in Huize De Ruiterberg bij Doorn, werd uitgevoerd door No. 322 Squadron, samen met de Spitfires van No. 66 Squadron ook van 132 Wing en gestationeerd op Woensdrecht. De school werd gevonden en de aanval laagvliegend uitgevoerd, waarbij de gehele voorgevel brandend instortte en ook de noordwesthoek van het gebouw zwaar werd beschadigd. Een verkenning toonde later aan dat het hele gebouw was verwoest. De enige Spitfire die deze dag verloren ging was van No. 322 Squadron, met F/S Kooij als piloot. Hij stortte neer bij de aanval op De Ruiterberg, vermoedelijk tengevolge van een bom, die voortijdig, vlak voor hem explodeerde, want luchtafweer was er niet. Jammer genoeg verloor Kooij het leven."

Source: Gerrit J. Zwanenburg, "...En nooit was het stil"; deel 2, blz. 530

2. Attack details

The Squadron attacked from Southwest to Northeast, diving in very low. The layout of the formal garden provided good aiming, so the attack direction chosen was the obvious one. The Spitfires carried bombs with delay fuzes set to 11 seconds. C. Kooij was not hit by the blast of his own bombs, but by that of one or two bombs dropped on target seconds earlier by one of the other attacking Spitfires, believed to have been flown by F/Lt. Jan van Arkel. The delay fuzes caught the aviator in a situation that these fuzes were designed to prevent.

There is uncertainty about what really happened. Gerrit J. Zwanenburg suspects that a bomb exploded prematurely, meaning earlier than the delay time of 11 seconds after impact. That would mean that C. Kooij attacked with a distance of no more than a few seconds after the other aircraft. If true, then the pilot's plan of attack foresaw this risk, and the pilots took it. The aircraft was hit, and the pilot subsequently killed, as a result of a technical malfunction.

However, we may wonder if this version is true. All technology involved may have performed as intended. C. Kooij's aircraft may have been hit as a result of unlucky inter-aircraft attack timing. If Kooij had attacked two seconds earlier or five seconds later, this would not have happened. But such timing accuracy has to be considered as beyond the means of the aviators, who had to make do with the circumstances of that time and place. They could not attack all together as a group; the target was too small for that. They had to attack individually, spaced in time so as to deal with the delay fuzes. They were professionals, who had made a plan of attack, in full awareness of the properties of the weapons they would be using. But they also had to attack as swiftly as possible, because there was always the danger of anti aircraft fire. They had to fly a high performance fighter aircraft very low, very fast, and very accurate over enemy-held territory. An enemy that was known to be very deadly with its anti aircraft defenses. Not a situation in which the aviator could coolly use a stopwatch clocked to the bombs dropped from a leading attacker. And even if that would have been possible, then the flying decisions had to be made well in advance. One cannot apply a handbrake to a Spitfire in the process of a high speed low level attack. The momentum of the moving mass is too great for that, and the margin for error too small. Waiting in the sky for say 30 seconds, so that the dust of the previous bombing run could settle, was not an option. That would give the enemy too much time to muster defences. These pinpoint low level attacks had to be flown fast in-fast out, with the highest speed that still allowed for accurate aiming. Attacking within say 3 seconds of each other was dangerous too. A bomb could explode upon impact, if the delay fuze failed. Everything had to be executed in a perfect way, in three dimensions and in time, the last measured in seconds only.

As it turned out, there was no Flak deployed at the Ruiterberg. The attackers could have taken more time for this attack. That this was the case, transpired not earlier than during the attack itself. And even then, the fire from a single German submachinegun at short range could have brought down a Spitfire. The loss of C. Kooij can truly be called a matter of bad luck, under both versions of what happened. The attack was carried out in an almost perfect way. Just two seconds from perfection for one of the aircraft. The mansion was completely destroyed.

3. Crash site data

The Ruiterberg, with its charming gate building, orangerie, farm, and large formal garden, was build by a very wealthy shipping merchant. The Nazis fancied such mansions for local command headquarters, transforming them into Allied targets.

Two small bomb craters, spaced 12 meters left and right of the flight path, can still be found in the wood directly adjacent to the Northeast stretch of the formal garden of the past. The only bomb craters found in this forest. Their shapes and sizes are quite similar, ovals of about 4 x 5 meters, 1,5 meters deep, ovals perpendicular to the flight path. We assume that the aircraft crashed into the pine trees here, after receiving damage from blast debris, with two armed bombs remaining, one under each wing. These trees were about 20 years of age at the time. We assume that the aircraft, flying at high speed, disintegrated upon hitting the trees, only a few seconds after the attack. The pieces were scattered over a small area in the wood; the wreck did not bury itself into the soil. The wreck parts could be cleared by the Germans with relative ease. Two days after the attack, the Germans buried C. Kooij as as unknown Allied airman in Doorn General Cemetery.

After the War, the Ruiterberg was rebuild. It is now a privately owned mansion in the Kaapse Bossen, owned by Staatsbosbeheer.

With thanks to Michel Reukers, forester Kaapse Bossen/Ruiterberg, who kindly guided us to the telltale marks in the terrain

Prewar aerial photograph of the Ruiterberg. The view is Northeast to Southwest. The 322 Sqn Spitfires attacked from the Southwest, top of picture, flying Northeast. C. Kooij crashed into the pine trees some 300 meters Northeast from the mansion, at the end of the lower section of the formal garden. Source: Staatsbosbeheer, with thanks to Michel Reukers

Two bomb craters in the flight path of the attacking Spitfires, the site where we assume that C. Kooij's machine perished in the wood. Ruiterberg 050913-2,3

The Ruiterberg in 2005, North facade. Picture taken 100 meters Southwest of the site where Spitfire RK840 came down. Ruiterberg 050913-4

Map 109. Ruiterberg, Doorn, crash site of C. Kooij

The blue circle includes the area where two bomb craters were found. These led to the assumption that C. Kooij's Spitfire crashed in this area in the wood. No other bomb craters have been found around the Ruiterberg mansion.

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