GCR,s Division, the 53rd Welsh played a major role in the capture of Jerusalem. The XXth Corps had advanced from the west across the Judaean hills but in the closing stages, at the beginning of December XXI Corps took over the main effort. 53rd Div advanced from the south through Hebron and Bethlehem to the outskirts of Jerusalem. Every effort was made to avoid fighting in the Holy City. By the 9th Allenby’s troops had the city completely dominated forcing the Ottoman garrison to withdraw. The mayor of Jerusalem came out and surrendered the city to the first British troops he found; a cockney cook looking for eggs. General Allenby entered the city officially, and on foot out of respect, on Dec 11th.
No letters from GCR until December 15th, not surprising one suspects they were a bit busy.