If he could start a damned war to end slavery in the south I'm confident he could have figured out a way to end the practice in his own states. If ending slavery was important enough to send federal troops to kill Southerners and shred the Constitution, why wasn't it important enough to do the same to Northerners?
Ummm
1) Lincoln didn't start the Civil War. Seven states seceded before he was even inaugurated on 4 March 1861. Even then hostilities didn't start until 12 Apr 1861, when Confederate Forces fired on Ft. Sumter.
2) The initial objective was to preserve the Union, not free or end slavery. Freeing slaves (not ending slavery) only became a war goal with the Emancipation Proclamation. And let's take a look a that document.
The Emancipation Proclamation was an executive order issued by President Abraham Lincoln on January 1, 1863, as a war measure during the American Civil War, to all segments of the Executive branch (including the Army and Navy) of the United States. It proclaimed the freedom of slaves in the ten states that were still in rebellion, thus applying to 3.1 million of the 4 million slaves in the U.S. at the time. The Proclamation was based on the president's constitutional authority as commander in chief of the armed forces; it was not a law passed by Congress. The Proclamation also ordered that "suitable" persons among those freed could be enrolled into the paid service of United States' forces, and ordered the Union Army (and all segments of the Executive branch) to "recognize and maintain the freedom of" the ex-slaves. The Proclamation did not compensate the owners, did not itself outlaw slavery, and did not make the ex-slaves (called freedmen) citizens. It made the eradication of slavery an explicit war goal, in addition to the goal of reuniting the Union.
The ending of slavery, making of freedmen citizens, giving them voting (and other civil) rights only took place with the passage of the 13th, 14th and 15th Amendments.
So to say the war was about slavery is to miss the point of the war. It was in essence over state's rights. Sadly the state's rights side lost simply because "the hill they staked their flag" (Slavery) on was and is morally repugnant.