They held this ground under enormous strain and pressure brought from without. Cross-roads assemblies, town and city meetings, and Commonwealth legislatures poured petitions and memorials in upon them in behalf of slavery restriction. The excitement, throughout the Northeast especially, was intense. They had to fight their battle under an ignoble issue. But it will not be denied by any impartial constitutional lawyer that they were, for this time, the upholders of the Constitution against an unwarranted attempt to stretch Congressional power.
Finally, the compromise provision, drawing the line of thirty-six degrees and thirty minutes through the Louisiana territory, and securing all north of it, which was by far the greater part, against the introduction of slavery during the period that it might remain under the exclusive jurisdiction of the general Government, was { 93} tantamount to a surrender, forever, of this vast domain to immigration from the North almost exclusively, and to the creation therein of new Commonwealths into which slaveholders could not take their slave property. Many American historians treat the express exclusion of slavery north of this line as no concession to the North, but as a mask under which the real concession, the concession to the South, was hidden. This they claim to have been the implied concession to hold slaves south of that line. But slavery was legal by custom in the whole of the province of Louisiana, when the United States received it from France. That is, a master might have taken slaves into any part of it, into which he might have gone himself, and would not thereby have violated any law, and the United States Government had not, down to 1820, changed this state of things by any act of its own.
The compromise upon the line of thirty-six degrees and thirty minutes was, therefore, a very decided limitation upon the existing rights of slave-masters. And even if slavery had not already penetrated into this region, it can hardly be claimed that the balance of advantage created by the compromise provision lay with the South, except upon the principle that the South ought not to have had anything, and the North ought to have had everything. Ethically, perhaps, this is the correct principle from which to judge the question, but politically and legally it was not, at that moment.