30 April 2023

Cornelius "Kor" Postma (Part Two)

by Claudia Hofstee

Note: This is the second of a two-part essay by Claudia Hofstee. Part One addresses Postma’s life story and Part Two is a detailed look at his involvement with looted art, especially with the Adolphe Schloss Collection.

Cornelius “Kor” Postma (1903-1977) moved to France in 1939 in search of better opportunities as a Surrealist painter. After the Germans invaded France in May-June 1940, he established professional ties with members of the pro-Nazi Vichy government like Jean-François Lefranc, who orchestrated the seizure of the Adolphe Schloss Collection, an internationally known collection of Old Master paintings assembled by Adolphe Schloss (1842-1910). Lefranc was an advisor to Darquier de Pellepoix (1897-1980), Commissioner-General for Jewish Affairs (CGQJ) under the Vichy Régime, and partnered with Bruno Lohse (1911-2007) a German art historian and dealer who served as Göring’s representative while deputy director of the ERR in Paris between 1941 and 1944.

The Schloss Collection was stored for safekeeping in August 1939 at the Château de Chambon in Laguenne south of Limoges (France). After its discovery in winter 1943, Vichy officials and German security agents confiscated the paintings on 16 April 1943. Postma provided the appraisal for the collection after its arrival and dispersal in Paris as an associate of Lefranc in the dismemberment and recycling of the Schloss Collection. Postma received 2,066,830 francs for his appraisal services. Lefranc received 10 million francs for his involvement with the seizure and dispersal of the Schloss Collection. The Louvre used its right of preemption on 49 of the confiscated Schloss paintings to build up its Dutch and Flemish rooms. Lefranc allegedly sold 22 of the Schloss paintings in late 1943 to a Dutch dealer known as Buitenweg, allegedly based in Amsterdam. Although Postma testified that he had met with Buitenweg in Paris, there is no evidence that this man ever existed. The prevailing theory is that Buitenweg was an alias for Lefranc. Why Buitenweg? The name Buitenweg may be a pun referring to a Dutch seventeenth century painter, Willem Buytewech I (1591/92-1624), who was based in Haarlem and Rotterdam. The painter was known by his contemporaries as gheestige Willem (Jolly William).

Postma consigned one of the 22 "Buitenweg paintings" by the Italian painter Giovanni Battista di l'Ortolano, Christ déposé de la croix with Galerie Claude, who then put it up for auction for him at the Hôtel Drouot in Paris. Another painting by Rubens, Paysage par un temps d'orage was sold for 60,000 Reichsmarks by Postma in June 1944 to Franz Rademacher (1899-1987), assistant director for the Landesmuseum in Bonn since 1936. The painting joined the collection of the Rheinisches Landesmuseum in Bonn. After the war, Rademacher handed the painting over to the French zonal authorities at Baden-Baden. The painting was restituted to the Schloss family in 1951 and auctioned off at Galerie Charpentier in Paris on 5 December 1951. Through the British art market, it ended up eventually at the National Gallery of Canada in 1998 (inv. no. 39709). Although Postma initially denied his involvement in the sale of the painting to Rademacher, a letter dated 29 June 1944 by Rademacher to German art historian Eduard Plietzsch (1886-1961) about the authentication of the artwork confirms Postma’s involvement.

Postma admitted to Allied interrogators that he had sold a Brouwer painting, Le Pouilleux, which depicts a man killing a louse, to Henri Verne (1880-1949), a one-time director of the Louvre for the imposing sum of 300,000 francs. The picture was listed for only 100 francs by René Claude Catroux who had provided Lefranc with a separate appraisal of the Schloss Collection in November 1943. Verne acquired the painting for Étienne Marie Louis Nicolas (1870-1960), a wealthy businessman based in Paris.

According to Elisabeth Furtwängler and Mattes Lammert, Postma was involved with another Buitenweg picture: a panel attributed to Philip de Koninck, Paysage. Postma sold the picture to the Berlin-based dealer and auctioneer Hans W. Lange (1904-1945) who then sold it on 12 August 1944 for 16,000 Reichsmarks to the Bomann Museum in Celle (Germany). Albert Neukirch (1884-1963) headed the museum from 1923 to 1949. Postma facilitated an export license to send two Liotard paintings to Lange. The picture was attributed to Philip de Koninck until the time of the confiscation of the Schloss Collection, but it was exported as a painting by Jan van Kessel.

Stormy landscape, by Jan van Kessel

One wonders when the reattribution took place, on whose orders -- Postma or somebody else?-- and for what reasons. In February 1946, the painting appeared on a list of works of art acquired by the Bomann Museum and the city of Celle since 1939. However, a British Monument Fine Arts and Archives (MFAA) officer, George Willmont (1907-1977), did not make the link between that painting and the Schloss Collection owing to its reattribution. Currently, the painting is still at the Bomann Museum. Since 2016, the museum has conducted extensive provenance research on their collection. 

In a 1946 letter sent by Postma to Albert Henraux (1881-1953), President of the CRA (Commission de Récupération Artistique), the French restitution agency, he argued that the paintings he sold came from his own collection stored in Switzerland before WWII and thus they could not have been looted. And this, despite his wartime track record. One of these paintings that he mentioned was a Guardi for which Postma arranged an export license in August 1944, intended for the German gallery Gerstenberger in Chemnitz. Moreover, Allied interrogators accused Postma of using Old Masters as payment for modern works. These exchanges may have taken place with the ERR. It is not known, however, from which collections (Jewish or not) these works came. It would be worth knowing if some of these paintings came from the Simon Bauer Collection that Lefranc, Postma’s partner in crime, had plundered. In October 1943, the Anti-Jewish commission (CGQJ) had appointed Lefranc as the administrator of the Bauer Collection.

In conclusion, we still know very little about the wartime activities of the Dutch surrealist painter, Cornelius “Kor” Postma. As of today, the majority of the 22 “Buitenweg/Lefranc pictures” are still missing. Every detail about their provenance is crucial to know who, through whom, how and when the paintings were sold after the seizure of the Schloss Collection in April 1943. Postma’s shadow looms large over the fate of these works.


Archives du Ministère de l’Europe et des affaires étrangères (AMAE), La Courneuve, France
209SUP_147_118: Bauer/Schloss/Buitenweg investigation Report Summary
209SUP_406_P48: Cornelius Postma
209SUP_480_P184: Undated pages from investigation report into Lefranc and Buitenweg
209SUP_482_P66 : 1945-1946 Postma file
209SUP_482_P67 1944-1946 Export issues re Postma
209SUP_482_P166 : Cornelius Postma
209SUP_482_P167: Interrogatoire Hermann Voss
209SUP_586_R45: List of 22 paintings for Lefranc/Buitenweg

Archives Nationales (AN), Pierrefitte, France
AN, 20144657/6, 06 July 1944, n. fol.

Published Sources

Galerie Charpentier, Catalogue de la deuxième vente de tableaux anciens de la collection de feu m. Adolphe Schloss, Paris, 1951, (lot 47).

Elisabeth Furtwängler and Mattes Lammert, Kunst und Profit: Museen und der französische Kunstmarkt im Zweiten Weltkrieg, 2022.

C. M. Galler and J. Meiners, Regionaler Kunsthandel – Eine Herausforderung für die Provenienzforschung?!, 2022.

J. Meiners and C. M. Galler, NS-Kunstraub lokal und europäisch: Eine Zwischenbilanz der Provenienzforschung in Celle (Celler Beiträge zur Landes- und Kulturgeschichte: Schriftenreihe des Stadtarchivs und des Bomann Museums), 2018.