The enemy's coal or the ally's

Italy possesses almost no coal. Its industry and railways depend entirely on it, and until the mid-1930s most of it came by sea from Great Britain. With the war, London tightens the blockade and prepares to declare German coal transported by sea to be contraband.

Two doors then open for Rome. London proposes a sweeping trade agreement: deliver several million tonnes of coal to Italy, and allow German coal to pass by sea, in exchange for Italian industrial supplies and armaments. Berlin, for its part, promises to deliver coal overland, by trains crossing the Alps at the Brenner, beyond the reach of the British fleet.

Accepting London ties the Italian war economy to the power Mussolini judges to be in decline and jeopardizes the rapprochement with Hitler; relying on Berlin shifts the entire burden onto a single Alpine railway line.