Reinsurance is a vital financial device for enhancing underwriting capacity, ceding risks, and mitigating financial distress. By supplying financial resources and services, reinsurance can facilitate growth and expansion in the insurance business. Focusing on the insurance sector in the emerging Spanish economy and using a novel dataset on fire insurance companies, this article examines the role of fire insurance in the national capital formation, the importance of reinsurance as a vehicle for expanding the country's domestic underwriting capacity, and how the import of capital impacted on the balance of payment, from the introduction of the first comprehensive legislation regarding insurance in 1908 to the outbreak of the Civil War in 1936. Considering the situation of undercapitalization, the singularities of the insurance market, and the changes in regulatory schemes, we find that foreign reinsurance became a key financial vehicle for increasing underwriting capacity in Spain. We also show the struggle of an emerging market to find ways to keep the balance of current accounts and raise capital when financial infrastructure was underdeveloped. The diffusion of reinsurance networks from the core of industrial western countries towards emerging economies was one of the mechanisms for financial modernization on a global scale.