Google Books has digitized Life Magazine and put it online. The famous article about Horrors of War is in the May 9, 1938 issue, p 4. Follow up letters to the editor (including one from George Moll, who produced the set) are in the May 30 issue.
http://books.google.com/books?id=0koEAAAAMBAJ&pg=PA4&dq=%22bridge+wanpinghsien%22&lr=&as_brr=0&as_pt=MAGAZINES#v=onepage&q=%22bridge%20wanpinghsien%22&f=false
