Lincoln’s main concerns about foreign policy had to do with the possibility that foreign countries might side with the South in the war or might at least recognize the independence of the new country.
One of the South’s major hopes for winning the Civil War was to get the French or (more importantly) the British to side with them. These countries could have put a great deal of pressure on the North to come to an agreement with the South. If this had happened, the North might have had to give in and allow the South to become independent.
This foreign policy concern was the most important issue that Lincoln faced. It was one of the main ways in which the South could have won the Civil War. This made it a vital concern in the area of foreign policy during the Civil War.