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.

16 April 2023

Cornelius "Kor" Postma (Part One)

by Claudia Hofstee

Note: This is 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.

Cornelis "Kor" Johannes Postma (1903-1977) was a Dutch surrealist painter who participated in the valuation and sale of Nazi-looted art during the German occupation in Paris. During WWII, he served as an expert for the German and French authorities. His involvement is well known with the valuation of the Adolphe Schloss Collection that he performed for the German and French authorities. The full extent of his wartime role in acquiring and selling looted artworks from French collections to German clients is still not clear.

Cornelis Postma was the son of Gerardhus Postma and Joanna van Doorn. He grew up in Hilversum (Netherlands). In 1923, Postma taught himself how to paint close to his hometown, in Laren. Later on, he received art lessons from the Flemish expressionist painters from Joseph Coutré and Gustaaf De Smet (1877-1943). The latter lived in the Netherlands from 1914-1922, He was also a pupil of Dutch artist Willy Schoonhoven van Beurden (1883-1963).

On 21 April 1926, Postma married a Jewish theater actress, Betsy Booleman (1901-1997). The wedding was held in Amsterdam.  A daughter, Heddy Ly Postma (1929-2017), was born three years later. While in Amsterdam, Postma worked for art dealer Pieter de Boer. In the 1930s, he collaborated in group shows with artists like Carel Willink (1900-1983) and Pycke Koch (1901-1991). However, due to disappointments in his career, Postma moved to Paris in 1939 where he worked as an artist until the onset of the German occupation in June 1940.

During WWII, Postma lived in a small family guesthouse at the Hôtel de Nice at 4bis, rue des Beaux-Arts (Paris). The street was known for its many galleries, bookstores, publishers and artists' homes. Postma changed gears and participated in the booming wartime Parisian art market. He befriended some notorious individuals such as art dealer Jean-François Lefranc, responsible for aryanizing Jewish-owned galleries and businesses in and around Paris. Lefranc was a close advisor to Louis Darquier de Pellepoix (1897-1980), Commissioner General for Jewish Affairs under the Vichy regime (1942-1944). Lefranc introduced him to Dr. Bruno Lohse (1911-2007), a Nazi art historian who served as deputy director of the Einsatzstab Reichsleiter Rosenberg (ERR) in France and coordinated anti-Jewish plunder for the ERR. He also met Kurt von Behr (1890-1945), Lohse’s superior at the ERR who supervised the ransacking of Jewish residences from 1942 to 1944 (M-Aktion). Postma’s knowledge of Dutch art and the Dutch art market made him an asset in Lohse’s network of French, German and other informants who persecuted Jewish collectors and dealers.  

Postma’s clients included art dealers like Munich-based Maria Almas-Dietrich (1892-1971) and Berlin-based Hans W. Lange (1904-1945)  to whom he sold a number of looted works. Lange used Postma to facilitate the export of paintings from France to Germany.  In July 1944, Postma exported three paintings; a landscape by the 17th century Dutch artist Jan van Kessel and two pictures by French artist Jean-Étienne Liotard (1702-789), Still life with pitcher and glasses (whose attribution was questioned) and Still life: Tea Set, which is part of the J. Paul Getty Museum in Los Angeles. 
Still Life: Tea Set, by Jean-Etienne Liotard

Still life: Tea Set was consigned to multiple French galleries for which Postma acted as a go-between with the actual seller. Michel Martin (1905-2003) curator at the Musée du Louvre, denied Postma his application for an export license for the Liotard painting mostly because the Louvre was keen on acquiring an important Liotard painting. This rejection of the export license illustrates one way by which French museums exercised their pre-emption right in the 1940s – a right granted to them by the Export Law of 1941. Despite Martin’s opposition, the painting left France in July 1944. Furthermore, Postma dealt occasionally with German art dealer Hildebrand Gurlitt (1895-1956), well-known art expert who had acquired thousands of works of art in occupied territories of Western Europe, mostly in France. 

After the war, Postma remained in Paris where he married his second wife, the Dutch artist Pieternella Wilhelmina (Lili) Bosman van Leer (1905-1966). Her first husband (1941-1949) was Oscar van Leer (1914-1996), a successful entrepreneur. Postma may have met Bosman through Oscar van Leer since Postma was acquainted with van Leer since the 1930s. This connection proved beneficial to Postma's postwar career especially since Van Leer had developed social ties with Princess Beatrix (1938-), crown princess of the Netherlands, and her husband Prince Claus (1926-2002), while organizing gatherings for artist and writers at their estate of Castle Drakensteyn. In the 1970s, Postma gave drawing lessons to Princess Beatrix's children: Willem-Alexander (1967-), Friso (1968-2013) and Constantijn (1969-).

Postma and Lili Bosman regularly had opportunities to hold joint exhibits in Paris as with Galerie Kleinberger in 1951. Postma also enjoyed solo shows at Galerie Vendôme in 1957 and 1958.



NARA RG 239 M1782 roll M1782_10F1
NARA RG 239 M1944 rolls 22, 44, 47, 52, 95
NARA RG 260 M1941 roll 19
NARA RG 260 M1949 roll 6

Archives Nationales (AN), Pierrefitte, France
AN, 20144657/6, 06 July 1944, n. fol.
Z/NL 381, 8841 (C), 379, Postma

Archives du Ministère de l’Europe et des affaires étrangères (AMAE), La Courneuve, France
Séries 370-555 Série P: archives de provenance diverse
209SUP/406: Cornelius Postma
209SUP406p48: Cornelius Postma
209SUP/482 P166 : Cornelius Postma
209SUP/482 P167: Interrogatoire Hermann Voss

Stadsarchief Amsterdam, 30561: Archief van Oscar van Leer 1920 – 2003

Noord-Hollands Archief, 358.6 burgerlijke stand van de gemeente Amsterdam, inv. nr. 2858, aktenr. Reg. 2A fol. 50v; inv. nr. 3105, aktenr. Reg. 1B fol. 46v

Published sources:

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

Vanessa von Kolpinski, ‘Art Transfers from France During and After the Occupation: On Export Regulation as a Protective Measure and Resulting Source Material’, Arts et politiques, 2022: 138-155]
-self-taught Postma

P.M. J. E. Jacobs, Beeldend Benelux: Biografisch handboek, vol. 4, Tilburg 2000, p. 668.

Jean-Étienne Liotard, Still-life: Tea Set, c. 1781-83, Los Angeles, J. Paul Getty Museum, inv. no 84.PA57.