My third and fourth Oregon historical romances were set in Eastern Oregon from 1865-67. This was a time of great change, inaccurate maps, and little real information even in the many small museums in the area. Read the newspaper columns from then and you quickly get how hysteria and misinformation in journalism is not new to today.
Even when I visited local museums, I found real information in short supply. They would have physical items from the earlier period but that doesn't really help a lot for the kind of story I was writing. How does the post office operate, how often to mails go through, how about the stage route-- daily or weekly? etc.
The complications of research can be shown by these images-- both of Watson but one Camp and the other Fort. 
My hero was serving as captain of this post on Fort Creek which is over one hundred miles southeast of The Dalles and a little less than forty miles west of Canyon City. When he served there, the post was called Camp Watson. There actually had been two Watsons. One was Fort Watson for the 1st Oregon Cavalry, all volunteers who were assembled in 1862 to deal with the Indian problems. They were disbanded in 1865 when the Civil War was over and federal troops were sent West. At that time, the fort was moved east and called Camp Watson. Or so might be the case and it lasted until 1869 when it was abandoned. If you read that link, you see the problem in all this-- many versions of the same 'fact.'
So the probability is this diagram of the fort is of the first Watson. The drawing might be Camp Watson. I have been in several old forts but all were considerably older than Watson as well as bigger. I looked for other sketches of small posts, the likely layout and found nothing quite as detailed.
The story goes that the first Camp/Fort Watson was abandoned as it did not have a good source of water. That would indicate the diagram of the fort's quarters is really Camp Watson... (I think the military downgraded some of these to camps to lower costs as after the Civil War, money was an issue). The photo below is during the period where Watson was a lumber camp.
My story is fiction. It is historical romance, not historical novel, but still I like it to be as close as possible to what life was like. The problem is how do we, today, decide what that was? It sounds good to do research, and I totally believe in it. The enjoyment of research is why I like writing historic romances. but it's not always easy to figure out what was a fact and what was an assumption.
