A French Trent Affair and the American Civil War

What if the Trent Affair involved a French mail steamer and brought France into the American Civil War?

French intervention would probably fail badly because the French fleet was already in a serious downward spiral.

The counterfactual moves the Trent Affair to a French mail steamer and asks whether France might fight Britain and intervene in the American Civil War. Such an intervention would probably fail because the French fleet was already in poor condition. Its later state around the Franco-Prussian War suggests a continuing downward spiral. Naval readiness would shape the outcome more than the diplomatic trigger alone.