The suspending of Habeas Corpus was not the only violation.
Here is a portion of an article I found at
http://shnv.blogspot.com/2008/12/true-estimate-of-abraham-lincoln.html
(this is a list of violations of the US Constitution by Lincoln)
"Coercion in 1861, Article IV.
Laws of Neutrality—Trent Affair. Article VI, Clause 2—Violation of international Law.
Writ of Habeas corpus Suspended. Article I, Section IX, Clause 2.
War Declared Without the Consent of Congress, 1861. Article I, Section VIII, Clause 11, 12.
Emancipation Proclamation. Article IV, Section III, Clause 2.
West Virginia Made a State. Article IV, Section III, Clause 1.
Freedom of speech denied. Vallandigham Imprisoned in Ohio. Amendment One.
Blockading Ports of States that Were held by the Federal Government to be still in the Union.
Liberty of the Press Denied. Amendment One.
Violation of the Fugitive Slave Law. Article IV, Section II, Clause 3.
How did Lincoln’s actions tally with his words? Was this honest dealing? Let us now quote the admissions of Lincoln’s own contemporaries in the North. Godwin, of The Nation, says: “The first real breach in the Constitution was President Lincoln’s using his war power to abolish slavery.
Thaddeus Stevens Stated: “I will not stultify myself by supposing that Mr. Lincoln has any warrant in the Constitution for dismembering Virginia.”
A. K. McClure, his friend, said: “Mr. Lincoln swore to obey the Constitution, but in eighteen months violated it by his Emancipation Proclamation.”
James Ford Rhodes said: ”There was no authority for the Proclamation by the Constitution and laws–nor was there any statute that warranted it.”
Wendell Phillips, at the Cooper Institute, said in 1864: “I judge Mr. Lincoln by his acts, his violations of the law, his overthrow of liberty in the Northern States. I judge Mr. Lincoln by his words, his deeds, and so judging him, I am unwilling to trust Abraham Lincoln with the future of this country.”
Percy Gregg said: “Lincoln (like Bush) never hesitated to violate the Constitution when he desired. The Chief Justice testified to this. Lincoln suspended the Writ of Habeas Corpus in 1861; he allowed West Virginia to be formed from Virginia contrary to the Constitution; he issued the Emancipation Proclamation without consulting his Cabinet and in violation of the Constitution.”
Charles Sumner said: “When Lincoln reinforced Fort Sumter and called for 75,000 men without the consent of Congress, it was the greatest breach ever made in the Constitution, and would hereafter give the President the liberty to declare war whenever he wished without the consent of Congress.”
Lincoln had no respect for the decisions of the Supreme Court, in the highest law in the land. As J. G. Holland pointed out: “The South stood by the decisions of the Supreme Court–The North did not and Lincoln did not.”
Abraham Lincoln himself stated in his Cooper Institute speech: “In spite of Judge Taney’s decision, Congress did not have the right to prohibit in the territories.” In his inaugural address, he said: “If the decisions of the Supreme Court are irrevocably fixed, Then people cease to be their own masters, and practically resign government into the hands of that eminent tribunal.”
To pander to the South’s vote, he openly said that any state had the constitutional right to secede if her rights were interfered with. Yet as soon as he was elected, he denied this and began to plan to coerce the seceding states back into the Union. He had openly said that coercion was not constitutional, and yet he called for 75,000 men to begin the coercion act without the consent of his Cabinet or Congress. He gave as his excuse that he could not afford to do without the revenue from the Southern states, and must prevent their withdrawal, right or wrong. This was the cunning that Seward said amounted to genius.
While insisting that the Southern states were still in the Union, on 19 July 1861, Lincoln declared a blockade, which brought untold suffering and privation on the people of the South. No nation can blockade her own ports. When England and France declared neutrality, Lincoln, fearing they would later acknowledge the seceding states as a Confederacy, issued his Emancipation Proclamation in the hope of conciliating them, though he acknowledged that he thought it would result in the massacre of the women and children in the South.
When the South, not desiring war, made every effort for peace, he blocked every effort that was made. When he learned of the Crittendom Resolutions before he was inaugurated. He sent word to every Republican member of Congress to vote against them. When he learned of the PEACE Convention presided over by ex-President Tyler, he sent Salmon P. Chase to represent him, instructed to vote against every comprise, especially against the return of fugitive slaves. And yet this man was the man who had said in Peoria, Illinois in 1854: “The slaveholder has a legal and moral right to his slaves. Fairly and fully I will give them any legislation for reclaiming their fugitive slaves. The master has the right to seize the runaway slave in every state in the Union.”"