Then the division took part in Operation Barbarossa; he was promoted to Generalleutnant and received the Oak Leaves to his Knight's Cross.

For health reasons he took actual command on 15 September, and was promoted to General der Panzertruppe on 17 December 1941.

[1] Crüwell was interned at Trent Park to the north of London, known as the "Cockfosters Cage", a Combined Services Detailed Interrogation Centre for senior officers operated by MI19 and equipped with an "M Room" listening facility to secretly record and translate the conversations of the inmates.

[3] Crüwell led the pro-Nazi group of German officers at Trent park, who were outnumbered by those opposed to the regime.

[4] The British intelligence files recorded in his character profile that "he tried to impress everyone with his own importance and knowledge, a trouble-maker and a bore".