A clue as to when the picture was taken might lie in Lindemann's cap having a white top. This was authorized for wear between 20 April and 20 September in home waters for service dress and walking out dress, but not usually for full dress. It is true that many U-boat commanders ignored regulations and adopted the white topped cap year round to make themselves more conspicuous, as did some surface ship commanders like Karl Topp of the Tirpitz, but Lindemann appears to have stuck to the letter of the dress codes.
Their shoulders held the sky suspended;
They stood and Earth's foundations stay;
What God abandoned these defended;
And saved the sum of things for pay.