Dutch Crypto-History

I uploaded a new article about Dutch crypto-history in Japanese ("オランダ暗号小史").
I started it as excerpts from Karl de Leeuw's book for my personal memorandum, but it grew into a bit more than that. I included some undeciphered ciphertexts I found in Thurloe State Papers more than ten years ago. For a long time, I thought the plaintext was in Dutch, but I now think French is more probable.