What did britain and france rely on the south for

They rely on them because of the raw materials to growbtheie investment in the south

Explanation:

The reason behind Great Britain's involvement within the American Civil War was primarily economic interest ... Not only were warships commissioned in Great Britain, so too were ships specifically designed to outrun Union blockade forces and smuggle illegal goods to and from Confederate controlled land.

British investment in the United States was considerable, and the cotton mills of northern Britain and Ireland relied on the Southern states for their raw materials. Industrial developments, notably the railways, were also often financed through British banks and companies.