John Jennings Creelman DSO KC BA GCL was born in Toronto, Ontario, son of Adam Rutherford Creelman and Margaret Cumming (Jennings) Creelman. In 1904, he had obtained his BA degree from the University of Toronto and in 1907 had obtained his GCL degree from McGill University, Montreal. In WW1, he served with the 2nd Brigade Field Artillery, 1st Division, Canadian Expeditionary Force.

On January 1st 1917, Creelman was awarded the Distinguished Service Order (DSO) for courage and gallantry in action against the enemy. At the time of the award he held the rank of Lieutenant Colonel and was with the Canadian Field Artillery. Although there was no citation accompanying the award, it is likely that is was connected with the exploits of the 2nd Brigade, Canadian Field Artillery during 1916.

After WW1, he was a partner in the Montreal law firm Creelman & Walsh and was president of several small companies and held directorships in others.

From 1921 to 1947, he was President, Canadian Artillery Association. From 1934 to 1940 he was Honorary Colonel, 2nd Montreal Regiment, Canadian Artillery and in 1940 assumed command of the regiment.

In June 1908, he had married Katharine Melanie Weekes, daughter of Mr. and Mrs. Nicholas Weekes of Galveston, Texas. Katharine died in 1918. His second marriage was to Maud Hamilton Slocum, daughter of Mr. and Mrs. Walter R. Baker.