Not only was he denounced by the abolitionists, but by the foremost leaders of the Republican party, such as Benjamin F. Wade and Horace Greeley, and received appeals from loyal people of the South, to whom he replied, with his usual patience, "What is done and omitted about the slaves is done and omitted on the same military necessity. I shall not do more than I can, and shall do all that I can, to save the government." In his view, military necessity was the only justification for the violation of the Constitution, which protected the slaves. In the second place, his delay was due to a doubt whether public sentiment in the North was prepared for a measure so radical and far-reaching; by his hope that the people of the border States would soon be willing to accept the act as a friendly as well as a necessary solution of a dilemma; and, finally, because of his profound respect for the Constitution which he had sworn to maintain. He would not free the negro because the Constitution stood in his way, and only for the sake of the Union was he willing to override that sacred instrument. This purpose was tersely expressed when, under great provocation, he allowed himself to violate his own rule and reply to Horace Greeley, who had attacked him in an open letter of unjust censure, accusing him of neglecting his duty. "I would save the Union," he said, frankly. "I would save it in the shortest way under the Constitution. If there be those who would not save the Union unless they could at the same time save slavery, I do not agree with them. If there be those who would not save the Union unless they could, at the same time, destroy slavery, I do not agree with them. My paramount object in this struggle is to save the Union, and is not either to save or to destroy slavery. If I could save the Union without freeing any slave, I would do it; and if I could save it by freeing all the slaves, I would do it; and if I could save it by freeing some and leaving others alone, I would also do that. What I do about slavery and the colored race, I do because I believe it helps to save the Union; and what I forbear, I forbear because I do not believe it would help to save the Union. I shall do less whenever I believe what I am doing hurts the cause, and I shall do more whenever I believe doing more will help the cause. I shall try to correct errors when shown to be errors, and I shall adopt new views so fast as they shall appear to be true views."