Both the great parties of the country had pledged themselves by the action of their national convention in 1852, to maintain the compromise measures of 1850, as a final, and satisfactory settlement of the slavery question in the United States, but the permanent success of the Democratic party was destroyed by an event which was intended to insure its predominance.
In 1854 Mr. Douglas, then a senator from Illnois, reported a bill from the committee on territories for the organization of the territory of Nebraska. Mr. Douglas afterward offered an amendment to the bill which referred to the Missouri Compromise, and declared "which being inconsistent with the principle of non-intervention by congress with slavery in the states and territories as recognized by the legislation of 1850, commonly called the compromise measures, is hereby declared inoperative and void, it being the true intent and meaning of this act not to legislate slavery into any state or territory nor exclude it therefrom, but to leave the people thereof perfectly free to frame and regulate their domestic institutions in their own way subject only to the constitution of the United States."
The proposition to repeal the Missouri Compromise, or declare it void, because of its opposition to the compromise measures of 1850, was received with reluctance; the people yielded to the Fugitive Slave law, only to discharge their obligations under the constitution, but when it was proposed to repeal the compromise of 1820, or to declare it inoperative because of its supposed conflict with the compromise of 1850, they were astounded. They had accepted the compromise measures of 1850 as a supplement to that provision of the compromise of 1820, which excluded slavery from the territories of the United States north of 36 degrees, 30 seconds.
No one can doubt that Mr. Douglas in his action upon the Kansas-Nebraska bill, committed the tactical mistake of his life time. He relied upon the strength of merely partisan organization. He did not understand what he afterwards found to be true; that the questions he had raised were of the most dangerous character and would destroy the Democratic party. There is no doubt but that the Dred-Scott decision and the assertion that congress had no right or authority to prohibit slavery in the territories of Nebraska and Kansas, gave birth to the Republican party.