1. Introduction 2. The European energy transitions 3. The emergence of a competitor: The impact of the development of electricity on the gas sector through Le Gaz Journal in the last third of the 19th century 4. Gas and electricity in Spain, between competition and complementarity (1880-1936) 5. The rivalry between gas and electricity in France and Spain through advertising and marketing (1890-1936) 6. The withdrawal of foreign capital in Spain's gas industry in the first third of the 20th century 7. The energy market during the Depression: gas and electricity in Spain and France in the 1930s 8. The impact of World War II on gas consumption in Western Europe 9. Iberian island rather than a peninsula? Gas pipelines between France and Spain since c. 1959: failures and achievements 10. Gas supply to France and Italy in the second half of the twentieth century 11. The Redevelopment and Repurposing of Historic Gas Site 12. Epilogue - EU, war and energy: geostrategy and gas pipelines