Hollis H. (or A.) Sampson
Illinois Civil War Muster and Descriptive Rolls Database (Illinois State Archives):
       Sampson, Hollis H. - Pvt - B - 100 IL US INF
       Residence, Jackson, Will Co, IL; Join, 28Jul1862; Age, 24; Born, Monroe Co, MI
       Height, 5' 6-1/2"; Hair, brown; Eyes, brown; Complexion, dark; Single; Farmer
       Trans to VRC (Veterans Reserve Corps) Jan(or Jun?) 13, 1865 Monthly return May 1865
American Civil War Soldiers (ancestry.com)
       Hollis H. Sampson - Pvt - Co B - 100th Infantry Regiment Illinois
       Residence, Joliet, Illinois; Enlisted, 28Jul1862
       Mustered out, 03Jul1865
Civil War Pension Index (ancestry.com):
       Samson, Hollis A.
       Widow, Samson, Emily P.
       Service:  Co B - 100 Ill Infl
                     Co E  - 23 VRC [Veterans Reserve Corps]
                     
Unas[unassigned] - 2 Battln VRC
       Date of filing - 1877Feb11 - Invalid - Certificate 1136.458
                              1918(?)Mar15 - Widow - NY
Civil War Soldiers & Sailors System Search Detail (National Park Service):
       Hollis A. Samson - Co B - 100 Illinois Infantry
       Soldier's Rank in - Private
       Soldier's Rank out - Private
       Alternate Name - Hollis A. Sampson
       Film Number M539, Roll 78  
National Graves Registration Database (Sons of Union Veterans of the Civil War):

Headstone Reading,

Will County Illinois USGenWeb Necrologist Reports (© 2002 The ILGenWeb Project All Rights Reserved):  

Published Obituaries:

Additional Biographical Material:

US Census Records:
    1880 - Joliet, Will Co, IL - Holis Sampson Household
         Holis Sampson, 44, born-New York - carpenter; Emily, 34; Milly, 11;
         Clara, 8; Hattie, 7; Flora, 6; Laura, 3; Hollis, 2.
    1910 - Rochester, Monroe Co, NY - Harris Sampson [Hollis Sampson] Household
          Hollis Sampson, 75, born-New York, Survivor of the Union or Confederate Army or Navy;
          Emily, 64.