[tz] question regarding Europe/Brussels in 1914

TZ zone Europe/Brussels has a transition from WET to CET on 8 November 1914:                         0:00    -       WET     1914 Nov 8                         1:00    -       CET     1916 May 1  0:00 What is the source for this information? Shanks, Henri le Corre "Regime horaires pour l'Europe et l'Afrique' and Gabriel "Trait de l'heute dans le monde' have all 4 August 1914, which was the begin of the German invasion. It seems unlikely that the whole country switched to German time at the begin of the invasion, and therefore I do not trust these three sources. Brussels was occupied by the Germans on 20 August 1914.