Lincoln opposed the Mexican-American war, believing that we were land grabbing by pushing Mexico into war over Texas. (he was right) I love all the adversity he overcome to get to the White house. The war changed him. At the beginning of the war, he thought the slavery issue was best settled by sending slaves to Liberia or other African places. But his thinking morphed, and the Emancipation Proclamation was the result. He was a good man, but the circumstances of his Presidency caused him to do things that are considered great.