Complex sentence: On 15 May 1941 he was posted to Inspektorate 7, the cipher bureau of the Wehrmacht (German Army) high command, although as an astronomer he knew nothing about cryptography and cryptanalysis.
Split into simpler sentences: On 15 May 1941 he was posted to Inspektorate 7, the cipher bureau of the Wehrmacht (German Army) high command. As an astronomer he knew nothing about cryptography and cryptanalysis.