How did the US respond when Europeans tried to create new colonies in the Americas during the civil war?

During the Civil War, the U.S. government was largely preoccupied with internal conflict and did not have the resources to actively prevent European powers from attempting to establish new colonies in the Americas. However, the U.S. issued the Emancipation Proclamation in 1863, which aligned with its long-standing Monroe Doctrine stance against European colonialism in the Western Hemisphere. This doctrine asserted that any European intervention would be seen as a threat to U.S. interests, but enforcement was limited due to the Civil War. Overall, the U.S. response was more rhetorical than practical during this tumultuous period.