That's Radical, not radical. Radical is not a slur here--it's a proper noun. Radical Unionists were a Missouri political party that integrated into the Radical Republican movement in the late war/post-war period. By late 1864 they were in full control of the Missouri legislature and the Missouri governor's office. On the Union side in Missouri, the Radicals were in opposition to the Convervative Unionists--very oftentimes in violent, deadly opposition. Think in terms of the heated rhetoric going on in our society today, and add armed individuals who had gone through four years of bloody conflict. That's how Radicals sometimes dealt with their allies--now apply that thought to how they would have dealt with their enemies.
Here is a very simplified overview of the Radical/Conservative issue: Radicals sought the immediate abolition of slavery and desired that the prosecution of the war in Missouri to be managed by the national government; Conservatives sought gradual emancipation, as well as state control of the military forces within the borders of Missouri (that is, they wanted state control for as long as they controlled the reigns of government in Missouri from 1861 through 1864).
Radicals were much more prone to act violently against a Unionist, slaveholding populace. And much much more prone to violence against a Confederate-supporting populace whether they were slaveholders or not.
All of that which has been written on Centralia describes it in terms of what was going on with the Confederates involved, both before and during the fighting, and the Confederate individuals who were involved. Except for the fight itself, nothing has been published in terms of what was going on with the intense, massive Federal pursuit of them that had been taking place for several weeks. Neither has there been a published profile of A.V.E. Johnston and his troops, and what kind of mindset existed that led them to such an ill-advised demise.
I have written a pretty thorough account of Johnston, his background, and that of his troops. Also, an in-depth analysis of the mindset that sent them into the abyss. Someday when I get the time I'll polish it up and publish it. I will tell you that they had been receiving orders from General Clinton B. Fish (yet another Radical) telling all Union troops involved in the overall pursuit leading up to Centralia to "take no prisoners," "destroy the devils," "strike with vigor," "pursue and kill," and "fight or die," while Johnston specifically was ordered by Fisk, to "Let the boys get after them. Make their presence and power be felt," as well to "bushwhack across the country" and to "exterminate the murderous thieving bushwackers."
Accounts that Johnston's men in the 39th Missouri Infantry were "raw troops" are in error. Take the names of Johnston's men and run them through the State Archives database--there are large numbers of veterans from the 1st PEMM and 2nd PEMM (which were experienced guerrilla-fighting units). Both units had earlier been disbanded by the then-Conservative Unionist powers-that-be for the Radical sentiments of its troops and their heavy-handedness in dealing with the civilian populace.
Also consider the account of a veteran of the 39th Missouri Infantry, 2nd Lt. John B. Draper (first cousin of the Lt. Col. Dan Draper mentioned in my earlier post), who wrote "Major Johnston had been ordered to follow and punish the bushwhackers. He had pursued them...had come up with them, and found the mangled and murdered corpses...lying festering in the sun; a village robbed and plundered, and the people paralyzed with terror. What was he to do? Turn about and flee away from danger, now that he was in its immediate presence? There are those who think he should have done so for the sake of his men; but they forget that his men were as eager as he to advance on the guerrillas."
Lt. Draper also stated "Major Johnston was a dashing fearless officer who had no doubt of his ability to successfully cope with any body of the enemy he might find; his experience as captain of an active militia company a year before having taught him that his greatest difficulty was to get at the enemy before they scattered to their accustomed hiding places amongst their friends...."
And, to illustrate the esteem in which his subordinates held him (a sentiment that ultimately led his subordinates to their deaths, en masse), note that which had been written about Johnston by one such subordinate prior to Centralia: "as a proper finale to this report I beg leave to say that the officers and men of my command all did their duty. We are all proud to have served under Johnston, who we believe follows the bushwackers to fight them on their own ground."