Public Domain | Copyright at UBC
4. Cinematographic works or a compilation of cinematographic work
Determination of whether a cinematographic work or a compilation of cinematographic works depends on whether or not the work was published prior to December 31st of the 50th year following the work's creation If a work was not published before December 31st of the 50th year following its creation, then it is considered "unpublished".
Published (i.e. published prior to December 31st of the 50th year following its creation) Enters Public Domain 50 years following the date of publication.
Unpublished (i.e. not published prior to December 31st of the 50th year following its creation) Enters the Public Domain 50 years following the date of creation.
Legally, you should be ok. Morally, you're using a dead ww1 veteran to peddle porn.