GT gets it, Walter Dunn;
It was on the internet, although the website discusses a number of early newspaper reports about Walter's adventures.
The following article about Walter was published in the Bendigo Advertiser on Saturday the 8th of April 1916.
STOWAWAY BOY SOLDIER.
Walter Dunn, aged 14, otherwise known as Charlie Chaplin, stowed away with the 1st Canadian Contingent, staying with them at Salisbury and Shorncliffe in England and then smuggling himself with the contingent to France, where he had many adventures, including a compound fracture of the left arm. He saw several battles, and was in the fighting at Loos. When he heard there was an army at Salonika, he look the train to Marseilles, found troops embarking, stowed away, reached Salonika, and has now attached himself to an Army Service Corps camp. Dunn is a great favorite with everyone, and makes himself really useful. His father is an officer in Princess Patricias Light Infantry.