WMU doctoral dissertations are all available, full-text, in the Dissertations & Theses database.
If you run a search in the Libraries' ADVANCED SEARCH, you may also find print copies of both WMU master's and doctoral dissertations that are available for checkout.
Try the following search:
1st box type history
2nd box type "western michigan university"
3rd box type thesis
Should you find a dissertation that is NOT full-text in the database, you can request it through Interlibrary Loan. About half of the colleges and universities in the U.S. will lend their theses, so you have a fifty-fifty chance of getting it.