Sean, don't despair too much--there are three early-postwar/early 20th century historical sources that state a block house existed contemporaneous to the existence of the Columbia Tigers (a Federal militia unit that was formed in early October 1864 and was disbanded by the end of that same month). One such source specifically places the construction of the block house as being October 1864. Bruce, if you could provide us with a cite for your source, perhaps analysis of it might shed some light on the matter. On the other hand, the three sources I refer to below were written after the war, raising the possibility that the memories of the subjects doing the reporting had melded the construction of the block house with the tenure of the Columbia Tigers, rather than several weeks after the unit was disbanded. It should also be noted that there was a successor unit to the Columbia Tigers that was called the Boone County Tigers that existed from April 21-July 31, 1865, and which almost certainly utilized the Columbia block house, which may have further confused the issue. Sean, even if the block house had not yet been constructed by October, the 3rd Missouri State Militia Cavalry had been headquartered in the courthouse in Columbia in the summer and fall of '64, and had it heavily fortified. They utilized the courthouse cupola as a lookout post (facts that could possibly be integrated into your novel).

Back to the block house -- a document entitled "Uneasiness and Excitement During Civil War," which is contained in the North Todd Gentry papers at the Western Historical Manuscript Collection in Columbia, states--"BOONE COUNTY'S ONLY BLOCK HOUSE. In October 1864, shortly after the Centralia massacre, a block house, made of logs, was built by James B. Ruckel, a Columbia carpenter and builder, for the Columbia Tiger company; it was built at the crossing of Broadway and Eighth. Like other block houses, it had port holes, so that soldiers in it could discharge their guns through such opening and be partially protected. The block house was located at the crossing so as to command a view of Broadway and Eighth for some distance. A large well was dug in the middle of Broadway, inside the block house, so as to furnish water in case of a siege. H.H. Banks says that he remembers that for some years following the war, the city hay scales were placed on Broadway by the side of that well, and that a part of the old block house was used. And John M. Samuel, in testifying in the circuit court in a criminal case in 1871, said that he was standing at the crossing of Broadway and Eighth, 'near the city scales.' A.G. Newman was then weigh-master. The city scales were later moved one block south on Eighth street, and C.C. Newman was weigh-master, and later Luther H. Crumbaugh. The well remained there till 1905, when Broadway was paved with brick, and the well was filled."

Compare to the 1882 "History of Boone County," at page 805. This source was published 17 years after the war--"Just after the invasion of the county by Todd's and Anderson's guerrillas, and the massacre and battle of Centralia, Columbia was placed under martial law. The able-bodied male citizens, irrespective of party or political sympathy, formed a company to defend the town against an expected and much-dreaded raid of the bushwhackers. A block house was built in the middle of the street, at the corner of Eighth and Broadway, to be used as a tower of refuge and of strength in the day of battle on of raid. The military company was called by the terror0inspiring name of 'Tigers,' the cognomen being supposed to indicate the fierce and desperate nature of the members, and giving fair warning to all bushwhackers to keep away...."

And the 1913 "History of Northeast Missouri," at page 272, in a section entitled "Columbia Tiger Company," states--"After hearing of the great destruction wrought by Bill Anderson and his men in other parts of the county, especially in and near Centralia, the citizens of Columbia, irrespective of their war feelings, joined a company for the protection of Columbia, its schools and churches. This organization had the bold and somewhat vicious name of 'Columbia Tiger Company,' and the members of this company were the first tigers who ever called Columbia their headquarters. James S. Rollins was elected captain, A. J. Harbinson and John F. Baker, lieutenants, and Lewis M. Switzler, sergeant. A blockhouse, made of logs, was erected at the intersection of Broadway and Eighth streets, suitable portholes made in the four sides and suitable military supplies placed therein. This blockhouse was built just over a well, which had previously been dug at the crossing of those streets, and thus plenty of water could be furnished the soldiers. The courthouse and Baptist church were used as sleeping quarters for the soldiers and both buildings were barricaded, and had portholes. They were surrounded by a ditch, which was intended to keep the 'Bushwhackers' from setting fire to a load of hay and running it up to the courthouse, and thereby burn the courthouse. Of course, sentinels were on every road leading from Columbia, and a watchman was on top of the courthouse day and night. By reason of the determination of the men composing this company, Bill Anderson and his cohorts never came to Columbia."