Lincoln wanted to keep the union together because of the threat of the Europe, and their designs of influencing and controlling the rising American power. Europe already had enthusiastic supporters amongst the southerners. The southerners wanted closer ties and allegiances with Europe. Lincoln, as an ardent supporter of a strong centralized United states, the beginning of an empire, would not allow the threat of European influence to come to the North American shores. Lincoln, as an intelligent man versed in economics, knew the Confederacy would inevitably come to depend on the Europe. This is why Lincoln was willing to save the Union at all costs, to create an American empire without any of the European powers to contend with on the American continent. This is why he would st brother against brother, in the bloodiest war (people killed per capita) in US history