In searching the internet for information on Josef, I have come across an interesting assortment of misinformation. Depending on where you look on the internet, for example, Josef was executed on:
a) August 13, 1941
b) August 14, 1941
c) August 15, 1941
d) none of the above
The correct answer is August 15, 1941. The death warrant was dated August 13, but it stated that the date of execution was to be on August 15.
Josef was taken from Wandsworth Prison to the Tower of London on August 15, 1941, and executed 7:12 a.m (certified by Lt. Col. C.R. Gerard, Deputy Provost Marshal of London District).
On a more personal note, the letter that Josef wrote to his family in the hours prior to his execution indicated that he would die on the Feast of the Assumption of Mary (August 15).