Source: Duty Nobly Done Roll of Honour 18th Bn. compiled and edited by Edward H. Wigney.
Family Search: Private Mark Arnold was born on 30 August 1881, in Paddington, London, England, United Kingdom. He had at least 1 son with Beatrice L. Paul. He immigrated to Canada in 1913 and lived in Willesden, Middlesex, England, United Kingdom in 1901. He registered for military service in 1914. In 1914, at the age of 33, his occupation is listed as labourer in Goderich, Huron, Ontario, Canada. He died on 9 August 1917, in Arras, Pas-de-Calais, France, at the age of 35, and was buried in Sains-en-Gohelle, Pas-de-Calais, France.
Note that a medical board recommended he be transferred from the infantry to military service that did not require much walking, as he had fallen arches. The board report is dated June 17, 1915. Pte. Arnold served with the 18th Bn. until he was killed in action on August 9, 1917.
Another Goderich man has given his life for the great cause. Word was received Monday that Pte. Mark Arnold was killed in action August 9th. Besides his wife, he leaves one son, Fred, who is with a forestry battalion in Scotland, and one daughter, Beatrice, at home. Pte. Arnold enlisted early in the war with the 18th Battalion, going overseas with the late Major Sale. He was thirty-eight years of age. The widow and children have the sympathy of the people of Goderich in their great loss.
The Signal, 1917-8-23, Page 1.
History of the 18th Battalion CEF, "The Fighting Eighteenth" 