How did the Union try to stop border state secession?

The Union implemented a combination of political, military, and diplomatic strategies to prevent the secession of border states such as Kentucky and Missouri. They emphasized the importance of these states to the Union's strategy and resources, deploying military forces to secure key areas and protect loyalist sentiments. Additionally, President Lincoln sought to maintain political ties by assuring border state leaders that the Union would not interfere with slavery where it already existed, aiming to quell fears and encourage loyalty to the Union.