What did lincoln believe regarding slavery and the importance of the union?

Lincoln often said that he had believed slavery was wrong for as long as he could remember. In a speech in Chicago on July 10, 1858 Lincoln said he of slavery: “I have always hated it, but I have always been quiet about it until this new era of the introduction of the Nebraska Bill began.” We see him as a strong leader who wanted to abolish slavery from the start of his presidency. However, there is another side of Lincoln that isn't well-known. He felt that restoring the Union was much more important that freeing the slaves.
At the beginning of Lincoln's presidency, he wanted reunification at any cost. He strove to avoid a civil war over the issue of slavery and urged to seceded states to rejoin the rejoin the Union. He felt strongly that saving the Union was his primary job. In his inaugural address, he stated, You have no oath registered in Heaven to destroy the government, while I shall have the most solemn one to ‘preserve, protect and defend' it. Lincoln felt that seceding from the Union was an illegal act, and it was his job to get the states back in the Union. Lincoln was personally opposed to slavery, but at this point in his presidency, he didn't want to interfere with pre-existing slavery.