A letter was sent from the Wounded & Missing Enquiry Department to his sister which stated "We have been trying to get information for you on your missing brother but have not been very successful up to present. One of the officers of his company 2nd Lieut J I T Scallon was interviews three days ago at the 5th Southern General Hospital, Milton Section, Portsmouth where he is a patient. He gave a report about your brother which shows that in the stress of battle he became reckless of danger. This is what he said about him "we were on the Vardar front, and on Sept 1st 1918 had practically taken our objective of Black Rock Salient . We were under a consented barrage and Sibley was believed to have been wounded. He was also suffering from shell shock and threw his away his rifle and equipment and ran laughing towards the Bulgar lines waving a pick axe handle".