>>4345Engels really nails it on the head, but it requires some detangling. Ultimately, the question is dubious in so much that whichever sort of trade the bourgeoise decide, it will never be in service of us. We can only benefit through trade's side effects. Engels in his support of protection, holds ambivalence, and justifies the policy practically. In practice, protection generates more wage labourers, thus protection is beneficial in this sense.
Seeing that free trade and protection are themselves not absolutes, it makes it hard to scrutinise which policy to support like Marx & Engels. Many people can give their economic reasons for supporting either case, but within the practical context of developing class power, the answer is dubious. I know in the case of Trump's protectionism, which is the most recent example of protection, it did significantly increase the amount of wage labourers. The United States is a post-industrial economy. Its uses of protection is purely political in nature. While at the same time, free trade has come with the effects of deindustrialisation and the degradation of living standards.