Mr. Stevens held that the clause bestowed upon Congress a "plenary, supreme, and unlimited" power over the states' governments, which Mr. Pendleton declared would subject every state in the Union to the caprice of Congress, which might at any time decide that any state government was not republican in form. Mr. Boutwell thought Mr. Pendleton's objection was not a valid one, for in his opinion, Congress had the right to change its opinion respecting any state government, and having once recognized it, could overthrow it if a controversy should arise concerning it. Mr. Sumner called the guarantee clause "the sleeping giant," and congratulated Congress that "the giant" had been awakened. He found in it authority for doing all things.
The change of the Federal Government from the theory of restoration to that of reconstruction, from the doctrine of the indestructibility of states, to the doctrine that the guarantee clause gave the United States power to demand such changes in the constitutions of the states as were compatible with the results of the war, has been insisted upon because of its importance. A knowledge of this change as well as of the ever-increasing tendency of Congress to set aside the limitations placed upon its action by the Constitution and to increase the number and scope of the conditions imposed upon the states, is absolutely necessary to a correct understanding of the history of reconstruction. In this change and in these tendencies is the whole history of the period. If the doctrine once be granted that the Federal Government could impose conditions upon the states precedent to the admission of Congressmen there was no logical stopping place short of the position of the Radicals that secession and war destroyed the state governments and put the peoples and territories under the control of Congress. Any position short of this was merely a matter of policy. Whenever it became desirable to carry the doctrine to its logical conclusion, men would not be wanting, who would do it. The Democrats and the Radicals held the only logical views, and they were the only men to adhere consistently to their views to the end. The one view found its warrant in the letter of the Constitution, the other in necessity and the laws of war.
The majority in Congress in 1864 held a middle ground and imposed rather mild conditions on the states. The Democrats and the Radicals held the two extremes. The majority agreed with the Democrats at the beginning, with the Radicals at the close of the reconstruction period. The time which the majority required to make this change from the one to the other extreme - from the doctrine that a state is indestructible to the doctrine that the maintenance of secession by force works a total abdication of all rights under the Constitution - was the time required to solve the problem of reconstruction. This change can be seen in a general way in the character of the different Congresses. The 37th Congress stood for restoration, the 38th Congress, for the Wade-Davis plan of reconstruction, and the 39th Congress, for the military reconstruction. But the change went on gradually and rapidly from day to day, and can readily be followed in the acts and utterances of Congress, which became more and more radical and revolutionary. Senator Browning, of Illinois, described the general tendency when he exclaimed: "Timid measures are treason now. It is bold, active, decided men, men with nerve enough to neglect precedent and all the past, and with resolute hand reach forth to grasp the future, that we want in this hour." Constitutionalism was ridiculed and every infraction of the Constitution and ancient principles of interpretation was justified by the plea of necessity. In the end the Radicals prevailed, and the boast of Mr. Stevens, that the majority would overtake him and go along with him, became a fact.
The Secession and Reconstruction of Tennessee by James Walter Fertig, pages 86, 97-99
PHD Dissertation in the Department of History
The University of Chicago Press, Chicago, 1898