You can find information on the service records for Canadian Soldiers of the First World War here:
Soldiers of the First World War - CEFThe search for "Morris" and "John" returns 69 possible soldiers. Do you have his service number?
There is also information on how to order the records from the Library and Archives Canada:
How to order a copy of a complete service fileWith regard to the possibility of your uncle being involved in the death of the Red Baron. --
Manfred von RichthofenRichthofen was killed just after 11 a.m. on 21 April 1918, while flying over Morlancourt Ridge, near the Somme River.
The RCR War Diary reports that on 21 April 1918, the Regiment was in the trenches in the "
LENS SECTOR"
Lens and Morlancourt are 50 kilometers apart, so it is unlikely he was involved if he was still with The RCR at the time.