Why a Union war with Britain would become a blockade trap

Would war between the Union and Britain have driven the Confederacy to renounce independence and reunite against Britain?

No. It would more likely have created a multi-front war, weakened the Union blockade, and encouraged Britain to support the Confederacy as its enemy's enemy.

A Union war with Britain would not have caused the Confederacy to abandon independence and rejoin the United States. Britain did not need to approve of the Confederacy to exploit it as an enemy of its new opponent. Even limited British support could have undermined the Union blockade and opened another front without giving the South enough aid to become an unconstrained power. The scenario turns diplomatic hostility into a concrete lesson about sea control, coalition logic, and the danger of multiplying wartime enemies.