It would seem that sometimes a story arises and repeats over and over again from a single speculation, until it becomes “common knowledge” – without any real substance in the sources.
Maybe the “Tau” crosses are an artifact. We could try to find the first reference to this claim and its source and as no one has found any contemporary representation, there is probably none.
1 / The Ritterbrüders would have a white tunic (a white surcoat in the war) with a black cross on the chest with a white cloak with a black cross on the left shoulder.
2 / The Sarjantbrüders would have a gray tunic (a gray surcoat in the war) with a black cross (but not a “Tau cross”) on the chest, but no cloak.
3 / The Halbbrüders or confreres would have a gray tunic (a gray surcoat in the war) without a cross and a white cloak with a black cross on the right shoulder.
The shields of all types of Ritterbrüders and Sarjantbrüders would all be white with a black cross (but not a “Tau cross”) and Halbbrüders or confreres could carry part of their coat of arms on their shields …
And it would be the same at the time of Grunwald …
And for the Knights of the Sword and The Knights of Dobrzyn, someone knows their rules – please see my topics on them -.