Hello James,

If your William H. Barnes was born around 1830-1840, and he died in 1936, he would have been close to 100 years old at death. The MD site mentioned a church cemetery in Maryland. The church may have death (burial) records, as well as the state archives.

When you find the right one, see if you can get a copy of a 'pension' record.
Also, if he really died in 1936, instead of 1866, then there would surely be a death record with, perhaps, a relative as an informant. While there is a chance of this helping you make the leap FORWARD to your family, there is a better chance of helping to trace the RIGHT family, with living descendants. (Perhaps you will meet on more familiar ground?)

There is a pension record for a William H. Barnes of the 38th US Colored Infantry (G). This matches the San Antonio 'marker'. Since the pension of this William H. Barnes was filed in Maryland, it may be helpful. It appears to be dated 1890 or '95, which is also consistent with the Maryland site's indication of death AFTER 1866.

The Texas site mentioned a military cemetery. There may also be a record of those buried in this military cemetery.

Finally, look at the history of the 38th.
The 38th was in Virginia until 1865, but was mustered out in Galveston in 1867. This doesn't conflict with a Texas death around 1866. Check the Military Forum for more methods and available records.

The Civil War site has a feature I hadn't noticed before. When you click on the soldier's regiment, there is a link for searching by name. Enter 'Barnes' - there were other Barnes in this unit. Any familiar names? Perhaps one of THEM is a relative of W. H.? Some of the other Barnes filed for Pensions. A few of the wives also filed for widow's pension from VA or MD or DC.

Of course, you can also view EVERYONE in the 38th.

Hope this helps - at least a little.