"Mr. Zylker notes that two important suppliers in Rotterdam, namely the Z.H.B. and Hengelosche, would not be among them. The speaker said that currently in Rotterdam Amstel H.B.M., van Vollenhoven and Oranjeboom are selling Dark Lager, the Drie Hoefijzers Semi-dark Lager, the Z.H.B. and some other breweries, Light Lager. The Z.H.B. has recently stopped complying with the Light Lager ban.
Mr Smits van Waesberghe says that the Drie Hoefijers can colour its Lager Beer darker when this arrangement is introduced.
Mr. Six says that the C.B.K. has always scrupulously refrained from intervening in existing interests, but the Speaker considers it justified with regard to Rotterdam to perpetuate a situation that has existed for 75 years and now threatens to go wrong.
Mr. Swinkels says that he will try to adhere to the Light Lager arrangement if the Kundenschutz discussed in this regard continues."
Minutes of the management of the CBK on 26th March 1941, held at the Amsterdam City Archives, document number 31121-1, page 212.
Neither ZHB nor Hengeloosche attended the meeting. Looking back, I see that it was always the same breweries who were represented on the committee:
Though I'm sure that both Z.H.B. and Hengelosche were members of the CBK (the Dutch brewers' organisation). I'm surprised that the ZHB, which was a substantial brewery located in The Hague, wasn't represented on the committee.
The obvious solution - shipping Pilsner instead of Ligh Lager - wasn't possible because of government restrictions on the percentage of a brewery's output which could be "heavy" beer. That is beer of the highest gravity that was allowed.
"Mr. van Waes suddenly hears about the Light Lager ban in Rotterdam. Speaker does not understand the difficulties. If Speaker's brewery were to supply Pilsener instead of Light Lager in Rotterdam, its heavy beer percentage would have to be increased.
Mr. Honig says that this is not possible, as the heavy beer percentage is set by the government.
After some further discussions, the board decides in principle:
a. the decision of the pub owners in Rotterdam to only deliver dark beer on some days, will be supported by the breweries with sanctions against violation;
b. the sale of Light Lager Beer in Rotterdam will be banned from 1 April;
c. Pilsener beer will not be supplied by other breweries to customers who no longer receive Light Lager Beer from the brewery supplying them;
d. an exception to the Light Lager ban will be: deliveries to the German armed forces in bottles bottled in the brewery itself;
e. points a to d will be communicated to the breweries as soon as possible in a circular, on the understanding that the provisions under c will only apply to the breweries that are part of the board, while before sending these circulars the ZHB and the Hengeloosche will be requested to join in the agreement."
Minutes of the management of the CBK on 26th March 1941, held at the Amsterdam City Archives, document number 31121-1, pages 212 - 213.
Note that German forces in Rotterdam would still be able to get light Lager. I guess German soldiers weren't that keen on Dark Lager.