Links to the Five Volume Set 

Online at the Making of America site

History of Pennsylvania Volunteers, 1861-5; prepared in compliance with acts of the legislature, by Samuel P. Bates. Harrisburg, B. Singerly, state#EBE9F0 printer, 1869-71.

Click on the title to read the volume page-by-page (to start, click on one of the page numbers, then after the page opens, just use the forward arrow > to access the next page).  Or click on Search to get the search box for that volume.