Fascinating discussion! It's probably still an error in my novel to have the blockhouse exist during Price's invasion, but considering that my Union captain is in the 90th EMM (note number) and gained his fame at the skirmish at Three Creeks (never happened) I'm obviously not going for 100% accuracy anyway.

Interesting that the blockhouse was of the "twisted" type with the top floor at an angle. This was a common and very effective type. As the article points out, it offered a complete field of fire. There were several blockhouse types, and much individual variation as local civilians designed what they thought best.

There seem to have been a fair number of blockhouses in existence before the order for all local militia to build them. On Marmaduke's first raid (31 December 1862 to 25 January 1863) he captured one and the commander of a second blockhouse burned it and fled before Marmaduke's advance. Supporting his raid, Porter got the Hartville garrison to surrender without firing a shot and torched their blockhouse.

Shelby's raid bagged several as well, including one at Lamine River railroad bridge.