I recently picked a nice WWI dogtag from a medical officer named Liva C. McLain, and found that he likely served as a surgeon with the 7th Evacuation Hospital at Chateau Montanglaust in France, a hospital especially equipped to deal with those wounded with mustard gas.

He is mentioned on page six of the following medical corps pamphlet,

http://jama.ama-assn.org/content/LXIX/25/2121.full.pdf

It looks like Liva served with the hospital during some key battles during the war.  His hospital served the wounded at both Chateau Thierry and Belleau Woods.  Here’s a good JSTOR article about the unit’s participation at Belleau Woods:

http://www.jstor.org/stable/3405593?seq=2&Search=yes&searchText=7&searchText=no.&list=hide&searchUri=%2Faction%2FdoBasicSearch%3Ffilter%3Diid%253A10.2307%252Fi278008%26Query%3Dno.%2B7%26Search.x%3D0%26Search.y%3D0%26wc%3Don&prevSearch=&item=1&ttl=1&returnArticleService=showFullText&resultsServiceName=null

Here is a link to a soldier in the 103rd Infantry Regiment of the 26th Division who spent some time recuperating at the 7th Hospital:

http://worldwar1letters.wordpress.com/2009/08/13/evacuation-hospital-no-7-at-chateau-montanglaust-8131918/

The 7th Evacuation Hospital was organized on 26 November 1917, at Fort Riley, Kansas, as Evacuation Hospital Number 7. The organization participated in WW 1…