Samuel Curtis laid out a thoroughgoing definition of treason for his Boston grand jury back on October 15, 1851. You had to conspire to resist the laws of the United States, or their enforcement. You must use or threaten force. You didn’t have to plan far ahead or come in full military panoply, but you did have to intend to oppose execution of at least one law in all cases rather than just in a particular instance. Through all of this, Curtis has largely written in the context of the act itself and immediate perpetrators, but he did specify that treason came out of conspiracies and combinations. How far could those reach, legally speaking?
It should be known also, that treason may be committed by those not personally present at the immediate scene of violence. If a body of men be actually assembled to effect by force a treasonable purpose, all those who perform any part, however minute, or however remote from the scene of action, and who are actually leagued in the general conspiracy, are to be considered guilty of treason.
That spelled bad news for vigilance committees out to aid fugitive slaves in their escape. If we take the laws of Kansas as those of the United States, an arguable proposition but probably close enough for proslavery Kansans, then it also implicated the entire Kansas Legion. They had a military band aimed at resisting the territory’s laws, which they hardly needed unless they foresaw the use of force to resist. The Legion’s constitution specified that once a group reached a thirty men, it must have a military character. Jacob Branson, his rescuer Samuel Wood, and likely everybody of consequence in the free state movement had membership in such a combination.
The sudden burst of warrants and eager exploitation of the crisis to seize the free state leaders in Lawrence still looks like an opportunistic fishing expedition in light of this, but one with at least a plausible legal leg to stand on. Legal niceties didn’t bother proslavery Kansans and their Missourian allies all that much, but they could honestly say they observed some of the forms.
Curtis spelled it out in words that anticipate free state political activity almost word for word:
Influential persons cannot form associations to resist the law by violence, excite the passions of ignorant and unreflecting, or desperate men, incite them to action, supply them with weapons, and then retire and await in safety the result of the violence which they themselves have caused. To permit this, would not only be inconsistent with sound policy, but with a due regard to the just responsibilities of men. The law does not permit it. They who have the wickedness to plan and incite and aid, and who perform any part however minute, are justly deemed guilty
Set aside the fact that Curtis had antislavery efforts in mind when he wrote all of this and I don’t see a great deal one could argue with. We might not reach for treason so quickly today as Curtis did, preferring some other offense, but his reasoning on each point appears sound and practical. His definitions don’t perfectly fit events in Kansas, but they come close. Given the real fear of slave revolt and already-extant inattention to the finer points of law, I come away from this with the strong sense that when most proslavery men said treason, they meant it. It served their purposes to make the claim, and some of the lawyers probably knew better, but it all fits together too well to read the accusations as entirely cynical.